Build a Left-handed Bass / Guitar From a Right-handed Kit

Building its own instrument is a very fun and entertaining activity, it also teaches a lot about the instrument itself, about how and why it works. Many guitar and bass building kits are available on the internet to ease your work by providing all the parts and components that you need, already cut and sanded. Most of the time you have the option to simply screw everything together and voilà, you have a functional instrument. However these building kits are very often, if not always, available only for right-handed players.

As a left-handed guitar player who wanted to build my own bass guitar, I had two choices : Forgetting about it or finding a workaround to build a left-handed bass from a right-handed kit. As you may guess I chose the second option.

This article is indeed about building an electric bass guitar but could easily be adapted to build an electric guitar. Please note that I am not a professional luthier and that some pieces of advice that I give may not be suited for high-end instruments (But high-end instrument are not built out of kits anyway).

Most of these parts came from the bass guitar kit I used. As a European resident, I ordered most of these part on Thomann, but you are of course free to choose any other seller. There are especially a lot of kits available on Ebay and a lot of parts available on Amazon. I used a Jazz-bass kit instead of a P-bass one since the electronics cavity seemed smaller, and this will become relevant in the next part.

• A bass guitar building kit (body, neck, pickups, electronics circuit, tuning pegs, bridge, pickguard screws...) : https://www.thomann.de/fr/harley_benton_bass_guit...
• Additional pickguard screws : https://www.thomann.de/fr/harley_benton_parts_pic...
• Some material to cut your custom pickguard, I used a sheet of plastic made for that : https://www.thomann.de/fr/goeldo_pickguard_black_...
• The finish of your choice (paint, wood taint, oil, wood stain...)
• A ton of sandpaper (I used grits 40, 60, 80, 120, 150, 180, 220, 320)
• Woodworking tool (preferably power tool) such as a bandsaw, scrollsaw or jigsaw.
• Wood glue
• A drill
• A wood rasp
• A router for the new electronics cavity. I have a few workaround if you do not have one.
• [optional] Additional electronic components (switches, push-pull pots...)
• [optional] Soldering tools (Soldering iron, solder, wires)
• [optional] Aluminum foil
• [optional] Double-sided adhesive tape

The first and arguably most important part of this build will be to come up with a design that you like for your instrument. You will be using the right-handed body that came with your kit. You have the option to leave it as is but in most cases, a right-handed body is not suited for a left handed instrument for several reasons : The cutaway for the fretting hand is not deep enough, the electronics are not on the proper side, same for the strap button, and so on.

You will be cutting your bass body in the right-handed one that you have. I recommend printing a template of the body that you bought in order to draw your custom shape on top of it. To my opinion there are a few rules to respect when designing the body shape :

• There should be a minimum amount of "changes of direction", meaning that the contour should not do zigzags, each curve should be frank.
• Use angles carefully : an angle adds "anger" to your design, be careful where you locate them.
• Remember that you will need to put two strap buttons : one on the bottom and one on up of the bass body.
• Do not remove too much wood or your instrument will be very prone to neck-diving.

If you choose to put the electronics on the other side of the instrument as I did, you will need to dig a new electronics cavity that should be large enough to put all your pots, switches and output jack in it, You will also need a custom pickguard that should cover both the former and newer electronics cavities. The two first advises for the design of the body also applies there. One could ask why I did not go for a brand new piece of wood and chose to work with a right-handed body. This is also an option, and probably a better option, but my reason is that it is not always easy to find a variety of wood that is suited for instrument making, and at a reasonable price. I found it easier to use the piece of wood that came with the kit, but feel free to use a brand new wood plank.

After I decided the design I wanted, I scanned it and re-drew the outlines of it on a computer. I used the path tool on the free software Gimp but this is only because I know how Gimp works, there are probably many software far more suited for this that you can use. I also scaled up my design in order to be able to print it on a regular home printer. Mine could fit on two sheets of paper (size A4) that I could then glue together in order to finally cut a paper version of my instrument. Now is a good time to make sure that your electronic components fit in the cavity you drew.

Some kits offer the possibility to cut a custom head on the neck by leaving a fair amount a wood to work with. I did not go too crazy with that and used a shape quite simple, but remember that you also have to design this shape, that should also match the "vibe" of the body and pickguard.

Now that you have a solid instrument design that you are eager to play, you are ready to start the actual woodworking. Use the printed version of your design to draw on your piece of wood. You may have to adjust some curves to fit your needs. Filling in the outside of the shape is a good habit to have in order to help making the difference between the inside and the outside while you will be working.

You can now cut this shape, please be very careful when using power tools, and wear adequate protection such as gloves and goggles in order not to hurt yourself. Make sure to let the saw on the outside on the shape at all times, since it will then be easier to sand unwanted bumps than adding wood to fill gaps. If you cut a little too deep in your shape, I advise to go with it and manage to get a nice curve rather than trying to cut in the complete opposite direction, which results in a shape not really pleasing to the eye.

I personally used a scrollsaw with a saw that is not really suited to cut through such a big chunk of wood. Indeed the saw broke several times even though I tried to go as slow as possible. I would recommend using a bandsaw, which is far more suited for this kind of job. A jigsaw could also do the job pretty well but maybe too well since then tend to be quite fast to remove wood. I also recommend keeping a small amount of the wood dust created during this process if you have holes to fill in your guitar body, such as pre-drilled screw holes, but we will come back to that later.

Do not forget to cut the head of your neck if you decided to do so now that you are at it.

If you have a router, use it to remove wood where your new electronics cavity will be. Make sure to work with small steps, not removing everything in one big pass. You can use a drill in order to removes cylinders of wood, not drilling all the way through the body, this will ease the routing process.

If you do not have a router and still wants to dig a new electronics cavity, you can try to work with a drill bit and wood chisels. And if you still do not have chisels, there is still the possibility to cut a hole through the whole body using your scrollsaw or bandsaw, but you will then have to create a backplate to hide this cavity from the back of the instrument as well.

You have the option to remove some wood in order for your instrument to be more comfortable to play with. I do not really have a guideline there, I simply used a wood rasp at a some angle in the middle curve of the instrument until it fitted nicely under my chest.

Also cut your custom pickguard after reporting its shape on the material you chose. My scrollsaw allows to cut at an angle. I used it to cut at an angle of 45 degrees since this results in a much cleaner pickguard in my opinion, allowing to see the multiples folds of it. If you decide to do the same make sure that you are cutting in the right direction, or the 45 degrees angle will be on the wrong side of the pickguard. I did this error for one edge of mine, but managed to fix my mistake by cutting again, this time in the right direction.

In order to cut a hole in the pickguard for your neck pickup, use this latter as a guide to draw where you have to cut. Then cut in the inside on this drawn shape, you can drill a hole in order to let your saw pass through the middle of it. You do not want the hole to be too big. Go very slowly in this process, verifying each time what side of the hole must be expanded by trying to fit the pickup through. My pickups have circular parts for the screws that are not as tall as the total pickup, this allowed me to make sure that the rectangle was of the right shape before trying to fit them. You can (and should) use sandpaper and rotary tools in order to be more precise in the amount of material you are removing.

If your guitar body came with pre-drilled holes for the pickguard screws that will now be visible due to the shape of your custom pickguard, you will want to fill them. Now is also a good time to fill unwanted cuts that will be impossible to sand from when you cut your body shape. You can use wood filler but I preferred to use the dust that came from my piece of wood in order to perfectly match its color. Just mix together some wood glue and some wood dust with a toothpick in some recipient until it is thick enough, then push this self-made wood filler into every hole and cut that you wish to see disappear. Let the wood filler dry for the indicated amount of time.

Now comes the most boring part of this whole build. But this is also the one that makes the difference between a well-made and a poorly-made instrument, so do not neglect it. You will have to sand everything down using ascending grits. I personally started at 40 and used grits 60, 80, 120, 150, 180, and 320. While it might seem to be a good idea to skip some grits, I do not recommend it since it will be much harder to make the scratches from the previous grit disappear. This process can be sped up using some rotary sanders or any power sander that you may have, but I did not have any so I had to do it all by hand. Do not forget to round up the edges of your instrument that you created when cutting its shape. Also do not forget to sand the head of the neck if you went for a custom one.

Now comes a really important part of this build : make it yours ! Add the colors that you want, paint, wood stain, burn the wood if you want to. The only important thing is that your wood has to be protected, so the final coat should be some kind of varnish or wood oil, depending on the finish that you desire. There are plenty of very good tutorials on how to apply a custom finish to a guitar on the internet such as Dan's ones from the Youtube channel "Guns & Guitars" that I strongly recommend, so I won't go into too much details in this section.

I personally went for a wood stain that I bought at a local store. This particular one is not really made for instrument making but I like the result and this is what really matters in the end. If you use some kind of wood stain make sure to buy a liquid one as they also exist in some kind of gel that is really difficult to work with. I applied two coats of it, but you can apply more if you wish for a stronger color. I recommend screwing a piece of scrap wood in the position of the guitar neck in order to be able to apply your finish to both the top and the back of your instrument at the same time.

Do not forget to apply some finish to the head of your guitar neck since it needs protection too.

Let it dry for at least a day.

You can now screw the neck in place. The neck pocket should be just large enough for it not being able to move, even without screws. Do not hesitate to add some very thin layers of wood on the sides of the neck if this is not the case.

In order to screw the bridge, make sure that it is aligned with the neck, you can use the lowest and highest string of the instrument to ensure that. It is also very important that the bridge saddles are as distant from the twelfth fret than the twelfth fret is distant from the nut at the top of the neck. If your kit came with pre-drilled holes, it should all be good, but this is not a reason not to verify.

Now that the neck and the bridge are in their sweet spots it becomes easy to put the neck pickup in place since it has to be aligned with the two outer strings. This pickup position should dictate the pickguard position since it is it that holds the pickup in place. Using these guidelines, put the pickguard in place and make sure it cannot move while drilling small holes through both the pickguard and the guitar body. The drill bit must be smaller than your pickup screws. You can then enlarge these holes in the pickguard only, since the screws have to fit entirely through, by except with their heads of course. You will also need to use a large drill bit to gently drill a V-shape to welcome the head of the screws, I used a V-shaped routing bit but a regular metal drill bit should do the trick.

This is actually part of the "Make it yours" step. Building its own instrument is also an opportunity to have custom wiring. You can go really crazy there : humbucker/single coils switches or push-pull pots, parallel/series between the two pickups, in phase/out of phase pickups, blending pots, killswitches... These options are not really expensive and can add a lot of sound possibilities when playing your instrument.

I personally kept the circuit that came pre-wired with my kit, only adding a parallel/series switch between the two pickups. I recommend the website guitarelectronics.com on which you can find many diagrams.

Grounding the strings is an important step to avoid noise coming from the pickups. Most of kits come with a pre-drilled hole between the bridge and the electronics cavity, you have the option to use this one if you want but this will result in a very long wire coming trough the former electronics cavity, next to the neck pickup and finally to the actual electronics cavity. I wanted to drill a new hole in order to avoid that, but I did not have a drill bit long enough and went for the long wire passing though the pre-drilled hole. If you decide to drill a new one, be aware that you will have to drill at a very strong angle, allowing for the drill bit to move and scratch the top of the body. Make sure to hold everything in place and do not go too fast.

This will also be the case with the bridge pickup wire whose hole has to be drilled again to avoid too long wires, although the hole is a lot shorter.

This part is optional but will help canceling the noise that will come from your pickups, especially if you plan to use distortion. The goal is to cover the entire pickup cavity with aluminum foil. Do that by adding successive stripes of aluminum to the edges of the cavity, using double-sided tape to keep them in place. Make sure to overlap the stripes in order to have a solid connection between all the stripes. You can test this connection using a multimeter if you have one. Do not forget to put aluminum foil in the back of the pickguard too, as the foil should form a continuous cage around the electronics cavity. The only exception is that the aluminum cage should not touch the neck pickup screws since it can cause shortcuts on some pickup models.

Now is the time you have been waiting for. It is time to assemble everything together. Start by putting the pickups in position, passing their wires through dedicated holes when needed, and adding springs at the bottom of their screws. Screw your pots and switches to your pickguard and solder the pickup wires in position if you have to do so. My kit came with small plugs so that I did not have to solder anything at this point. Screw the pickguard in position, this might be a little difficult since you will have to push into the cavity any excess of wire. You can then screw the pickup roughly at a good height. Add the string retainer on the headstock if your kit came with one.

Before putting strings on your instrument, remember that the nut was designed for a right-handed setup, you will indeed have to reverse it. If it is glued in place as mine was, use pliers to hold it firmly and gently apply back and forth motion to pull it out. Do not apply too much strength or you may deform, even break it. Once the nut has been pulled out, reverse its direction and glue it back in place. A very little amount of glue suffices since it will stay in place mostly because of the strings pushing it onto the fretboard. Add the tuning pegs to the headstock. You may have to drill holes for that if yours was not pre-drilled. Mine was, but I had to sand a little amount of wood in order to fit the tuning pegs washers.

Do not forget to install strap buttons onto your instrument. One of them obviously goes at the bottom of the instrument, but the location of the second one is up to you. On most guitars and basses, it is located on the upper "horn" of the body, but in my experience this position can lead to an instrument very prone to neck-diving when playing standing up. I recommend drilling a hole in the neck plate using a metal drill bit in order to put it there, this is the safest position allowing for a well balanced instrument, especially since we removed a lot of wood from the original body.

Add strings to your instrument, you are almost done !

Before trying to play, make sure to give your beautiful instrument a decent setup (intonation, pickups height...). Again there are plenty of good tutorials on the internet on how to do that. I once more recommend the Youtube channel "Guns & guitars" that has very comprehensive videos that briefly covers everything you need to know about bass guitars setup.

At this point I realized I forgot to add a personal signature on my instrument and decided to cut my initials in the excess wood from the headstock. Feel free to add anything you want on yours. I know that a decal is not very difficult to do using a printer and some adhesive tape.

Tune the instrument and get ready to jam !

If you have any question on this build feel free to leave a comment and I will try my best to answer you as fast as possible !