BANANA CANDLES MADE WITH PLASTER AND 3D PRINTING

I saw this weird banana candleholder somewhere on the internet and I failed to save it, so I was forced to make my own version.
This candle/candle holder consists of two parts- top part is candle and bottom part is plaster. If you plan on actually lighting the candle, you can save the 3D printed mould and make more candles in the future.

I'm also showing an example on how to use MOLD setting in CURA and how to cast plaster in 3D printed moulds.

• 3D PRINTER
• PLASTER OF PARIS/GYPSUM/CEMENT (OPTIONAL)
• CANDLE WAX, WICKS
• SANDING PAPER, SCALPEL, FILLER/PUTTY, DISPOSABLE GLOVES
• BRUSHES, ACRYLIC PAINTS, TOUGH EXTERIOR VARNISH

I used https://www.thingiverse.com/thing:3664845 as a base for my banana, tweaked it roughly to thicken the peeled sides and added an exposed banana part. Both pieces are overlocking, candle part will fit seamlessly within the plaster part.

This part can be printed as you'd normally do and then processed. So, sanding, filler, paint, varnish, as usual.

I was dead set on using plaster to try and recreate some rough plaster texture and I decided to experiment with covering PLA print with a layer of plaster.

Once I printed it in PLA (not a good quality print, 0.3mm layer height, 15% infill, 3 walls...mainly to save time, I had other projects waiting to be printed), I covered it in a thin layer of plaster. I wasn't too optimistic, plaster usually doesn't stick to plastic, but somehow it turned out alright.
First, I used a sanding paper (40 grit) to rough the print up. Then, I mixed a small amount of plaster of Paris (reinforced plaster) to the consistency of heavy cream and used a disposable brush to apply it all over the print. I let it dry, sanded it and added second layer before sanding again.

There is a magical feature in CURA, that allows you to make moulds (or molds). I have no idea what the intended purpose of this setting is, but I've been using it to print moulds of busts and statues, flower pots and really, anything that could be cast in plaster.
All you have to do is go to settings in cura and type MOLD to see your options. Click all available options and you are ready to experiment with moulds.

Here are some tips:
-It takes about 2x longer to print a part in mold setting than in normal setting.
-Print with thin walls- 1-2 walls, but preferably just a single wall
- You have to print with an infill, depending on the size and shape of your part, you will have to use between 5 and 15%. You can't print without it, it will be too flimsy and plaster will cause the plastic mould to bulge.
-Pay attention to retraction settings, you don't to end up with stringy parts, especially on the inside, where plaster will go.
-Certain shapes will require supports. This again will have to be closely monitored. Wrong settings like wrong overhang angle or support placement can mess your print. Basically, you don't want supports being printed inside the mould in places where you won't be able to remove them.

Once it's printed, take a look inside and make sure there are no holes stringy bits. If necessary, clean it as much as possible, remove supports and if you have any holes, cover them with filler or putty. There shouldn't be any holes if the print is good quality and your printer is well calibrated.

-Mix plaster (or cement) with water and pour it into the mould.

-This part had some small, tight places, so I poured plaster into a piping bag, taped a short length of plastic straw to the tip and used this contraption to pour plaster into all those tiny holes.

-Leave it to set. I can't stress it enough- leave it for days. You want it to be fully cured, not just set, otherwise plaster will crack once you start removing it.

-Once it's cured, use a combination of (mostly makeshift) tools to remove the plastic mould.

-I used dremel to cut through the first wall of plastic and then used a small tool to peel the most inner wall --> https://www.amazon.co.uk/Rolson-59137-Wax-Carver-S...

-Sand the plaster.

Use acrylic paints and/or spray paints to decorate the lower part of the banana. I went with strong colours inspired by pop art.

Ready to print mould for the candle part. Mould has keys for easy and fast interlocking and elongated edges, so paper clamps can be sued to hold the mould together.

-The inside of the mould had a bit of a rough texture and I wasn't sure if it will be a problem later on, so I applied a layer of tough, outdoor varnish to the inside of the mould.

-I assembled the mould with paper clamps and used a hot glue gun to temporarily attach the wick to the top of the mould. I also used more glue around the top edges to make sure wax doesn't seep out.

-To keep the wick straight, I secured it with got glue and toothpicks (pic.3)

-Melt yellow wax candle and cool it to 65-70 C, pour it into the moulds and let it cool down.

-Unmould and use a scalpel to trim the edges (if necessary).

-Place the candle into the plaster base.