Digger/loader Costume With Working Bucket and Lights

Like many kids his age, my toddler loves diggers and loaders and other heavy machinery. I thought it would be fun (and he was keen on the idea!) to build him a digger costume for Halloween. I wanted to make sure it had at least a few interactive elements, so I added a bucket that can lift and tilt and a couple of lights with a switch that he can easily reach.

Note that I'm referring to this costume as a digger, even though it's technically a loader. Making a working digger with a long arm and bucket was a bit too ambitious for this year, but maybe that'll be a project for the future :)

1. Cardboard box: This forms the main structure of the costume. I used a baby wipe box that is made of double-layered corrugated cardboard and is approximately 15.5" long, 13.5" wide, and 11" deep. It's very sturdy and has held up well with a week of use and abuse. For the bucket, I used a different box and folded and cut it to the dimensions I wanted.
2. Plywood: I used a mix of 3mm and 6mm Baltic birch plywood to create the framework for the bucket mechanism.
3. PVC pipe: I had some leftover 3/4" PVC from another project and so I used that as the rotation axis for the bucket mechanism. Threaded rod, other types or sizes of pipe, or a dowel could also work well.
4. LEDs/batteries/switch: I used two white LEDs, a 9v battery, appropriately sized resistors, and a scavenged switch for my light circuit.
5. Clear acrylic: I cut acrylic pieces to fit over the LEDs for the lights.
6. Bolt/nut/washer kit: The kit that I used is from Princess Auto (Canadian store somewhat similar to Harbor Freight). They're quite cheap (and go on sale relatively often!) and come with a bunch of different lengths of #6 and #8 bolts, as well as nuts and washers which are super convenient to use for a project like this. Highly recommend picking one up!
7. Threaded rod: This is used to help couple the lifting lever and arms to the PVC pipe to control the bucket lift mechanism. I used a short piece of #8 threaded rod so that I could use nuts from the kit above. A bolt/nut combination could also work well if you had the right length of bolt available.
8. Poster board: The digger is pretty much entirely covered by yellow poster board that's glued onto the cardboard box with spray adhesive (huge thanks to my wife for doing this part of the project!). The tracks and lettering are made from black poster board.
9. Strap: I had some 1" nylon webbing laying around that I ended up using for shoulder straps. Rather than buying clips/buckles to make it adjustable, I just laser cut a couple of clips out of 3mm plywood.
10. Glue: I used a mix of wood glue, super glue, and hot glue to hold things together.
11. Furniture pads (optional): My son is not a huge fan of actually carrying the box with the straps and prefers to just scoot it along on the floor in our house. To help it slide a little smoother, I stuck furniture pads to the bottom of the box.

I didn't take any photos of this step specifically, but these photos from later in the process show the idea pretty clearly.

The top of the box for the costume is actually the bottom of the original box. The hole in this side of the box was made by tracing and cutting around a dinner plate [photo 1].

For the bottom of the box, I left a couple of inches of each flap hanging down to provide some additional rigidity to the box [photo 2].

I sketched out the rough shape of a bucket that seemed to be a reasonable size based on the cardboard box that I was using [dimensions shown in photo 1]. If the sizing works out, it can be really helpful to use an existing cardboard box and essentially just cut off one corner of it to use as a bucket.

The back face of the bucket is sandwiched by a couple of pieces of plywood for strength [photos 2 and 3]. These pieces are the connection point between the bucket and the body of the digger and are detailed in future steps. I made sure to attach the panel to the front of the plywood before covering it with poster board.

The bucket is controlled by two levers - one for lifting the bucket, and one for tilting it. A piece of PVC pipe forms the main axis of rotation for the levers. This entire mechanism is designed to fit inside a frame that is glued into the front of the main body of the digger.

In the attached photo, the main parts of the bucket mechanism are labeled for reference. Further details about their operation are described in the following steps.

As noted, the cutouts in the top of the frame are for the lift and tilt levers, LED lights, and light switch.

The back plate of the bucket is the same as shown in the 3rd photo of step 2. It includes a spot for the linkage to connect to and two half circles with holes in them that allow the bucket to rotate as the linkage moves.

Lifting mechanism

The lifting lever works by rotating the entire PVC pipe, which in turn rotates two arms that lift the bucket. Photo 1 shows the lift lever connection, and photo 2 shows the connection of one of the two lift arms.

The lever and two arms are coupled to the PVC pipe using threaded rod and nuts that pass through the pipe. Cutouts in the lever and arms slide over the nuts and are hot glued into place to prevent them from moving. Photos 3 and 4 show the threaded rod setup more clearly.

Note also in photo 2 the additional ring that was added to the frame to support the PVC pipe and isn't shown in the photos in step 3. This ring likely isn't necessary, but provides a bit of extra support.

Tilting mechanism

The tilting lever rotates independently of the pipe, but pushes and pulls on a linkage connected to the bucket to tilt it.

The attachment point for the linkage on the tilting lever is shown in photo 1 and is connected to the linkage with a bolt.

On the bucket, the linkage attachment point is on the plywood panel on the back of the bucket. The bucket rotates around a couple of bolts that connect it to the lifting arms. The linkage itself is laser cut out of a piece of plywood. So far it has held up, but a more robust material may be better for heavy use.

Photo 2 is of a test version of the mechanism that I designed that I think shows the principle of operation of the mechanism more clearly. The only differences between the test version and the actual mechanism used are the location of the linkage (above vs below the pipe) and the combination of the lifting lever and one of the lifting arms in the demo version. The actual mechanism separates the lifting arms from the lifting lever. The video shows the functioning of the demo version.

If I could go back and do things differently, I would definitely change the way that I designed the lift/tilt mechanism for assembly. I started by building the overall frame with holes in the side for the PVC pipe to slide through. This made it very challenging to attach the levers and lift arms as I had to slowly slide the pipe through the hole in the frame then slide it through a lever or arm, glue that piece on if necessary, and keep sliding the pipe through.

If I were to do things differently, I would cut a slot instead of just a hole in the side panels of the frame. That way, I could attach all of the levers/arms to the PVC pipe where they're easily accessible, then slide it into place all at once before locking it into place in the frame (with another piece of wood, some kind of stop, etc.)

Getting the lift/tilt mechanism into the body of the digger was a bit of a challenge, but I got it in and glued it in place after a bit of wrangling! I had to pre-cut slots in the cardboard that would allow the levers, lift arms, and linkage to move and then slowly tilt/slide/glue the frame into place.

All of the pieces are bolted together with washers between any parts that need to rotate against each other. It was pretty tricky to thread the nuts on some of the bolts, but I was eventually able to get them all connected!

The tracks on the side of the digger were designed in Inkscape and consist of a layer of wood with black poster board glued to it. On top of that are three round yellow poster board circles that represent the drive system/rollers, then anther piece of black poster board with the track pattern cut into it. I didn't take any photos of the assembly of these parts, but they're pretty straightforward to put together.

I originally thought that I wanted to mount the tracks so that they extended below the bottom of the main box. I'm very glad I didn't though, since my son often just pushes the box around on the floor, so they would have been quickly destroyed if I had done that!

The strip that the text is cut out of is made of black poster board. I used the font Overpass for the text. Make sure to save the islands (the small cutout pieces in letters like A and O) if you end up doing something similar!

Note that the actual digger has his name on it, but I've removed it in the photos for privacy.

I didn't want to have bare LEDs sticking out of the top of the digger, so I added acrylic pieces to be edgelit to diffuse the light a little bit. They're simply designed as a half circle with a cutout in the bottom that snugly fits around the LED [photo 1]. I originally hoped to add some red LEDs to the back as well, but didn't end up having time to get those put in before Halloween.

The slots for the acrylic pieces are cut into the internal wood frame structure (shown in step 3) and need to be cut out of the cardboard as well. The acrylic is glued in from the top, then the LEDs are glued in from the bottom [photo 2].

I sourced the light switch from the miscellaneous parts bins at the makerspace that I'm a member of [photo 3]. It seemed perfect for this project, so I cut a plate to fit around it to mount to the front of the digger. The cutout for the switch also needed to be cut out of the frame, so I accounted for that in my design then cut the cardboard out of the box once that was in place. A couple of small bolts and nuts hold the switch securely in place.

I am not very good at electronics design and am terrible at soldering, but this was an easy enough project to wire up. I didn't want to have to solder everything in place inside the costume, so I used a couple of connectors (one barrel jack and one clipped servo extension cable) to separate the components and make them easier to assemble in the tight space of the costume. I used a 9 volt battery since it's easy to swap and should keep the lights on for quite a while. Photo 1 shows the switch location and attachment plate between the levers.

The LEDs and resistors that I used were also sourced from the makerspace miscellaneous parts bins. I assumed 3v forward voltage and current limit of 20mA for the LEDs, so I calculated a required resistor value of 300Ω. Thankfully most of the resistor bins are well-labeled at the makerspace, so I was able to easily find the right value from there. Photo 2 shows the layout of everything within the costume, and photo 3 shows (I think - again, this area is not my specialty!) an accurate circuit diagram that I created with https://www.circuit-diagram.org/.

Everything ended up working well. It's a bit of a mess of wires and tape holding things together inside the costume, but the circuit hasn't failed yet!

The costume ended up being quite front-heavy, so I attached the straps as far forward as possible to try to balance it out. The straps cross at the back to make them stay on a bit better, but my son still wasn't a huge fan of carrying the costume with the straps! Using the wood clips that I cut out, it was fairly easy to lock the straps in place and adjust them as needed. If you're looking for a source for short lengths of strap for relatively cheap, a well-equipped sporting goods store might have what you need and sell it by the foot/meter.

The lettering and tracks are attached with a mix of super glue and glue dots. I also glued a small piece of wood across the tilt lever slot as a stop to prevent the bucket from tilting too far forward.

I occasionally need to re-tighten the nuts and bolts. Locknuts or jam nuts may help prevent this, but it's not too big of a problem to deal with on occasion.

The whole frame structure in the front of the costume made it quite heavy overall and especially front-heavy, so my toddler wasn't super keen to wear it. If I were to do things differently, I'd probably use exclusively 3mm plywood (6mm seemed like overkill for most parts) and cut down the size of the frame drastically. Either make it thinner (front to back), or only add support rings for the PVC pipe and a few other key pieces of reinforcement.

I'd also add some kind of stop rings or pins on either side of the tilt lever. As the lever is moved backward and forward, it shuffles side to side a bit along the PVC pipe and can eventually get a little jammed up inside the slot in the frame that it slides in. Adding stops would prevent it from moving side to side and avoid this issue.

In the end, it still turned out really well! While we didn't wear it long for trick-or-treating, it's turned into a fun toy for my son to play with at home. I added furniture pads to the bottom of it so he can slide it around easily on the floor, and he loves sitting on the back or crouching inside to play with it. I've been very impressed with the durability of the cardboard as well. It's held up perfectly over the past week, so we'll see how long it lasts!

I've attached an SVG file below for the main frame and lift/tilt mechanism. A few notes:

1. The corner supports and top and bottom of the frame are designed for 3mm plywood, and the sides of the frame and all levers are designed for 6mm plywood.
2. I left out the cutouts for the switch and LEDs in this file, since that is highly dependent on the size of switch used.
3. The slots in the top of the frame are a bit too narrow for the levers to slide freely, so the slots or levers need to be sanded or cut down a bit to move smoothly.
4. The file doesn't include holes in the panels that attach to the back face of the bucket. I drilled those out separately after the pieces were cut.

Please let me know if you have any questions or would like clarification on any steps and I'd be happy to help!