Introduction: Mario Goomba Costume

So this is a costume of a Goomba character from Mario that I just made for my 4 year old for Halloween but it also fits me (a 5'11" adult). It is made from cardboard (so it's lightweight) and some 3D printed pieces. If you don't have a 3D printer, you can easily replace the eyes, tongue, eyebrows, and teeth with some cardboard cutouts of these things (would make the costume even lighter). It wouldn't be as 3D, but would still look great. Im not trying to discourage anyone from skipping this project due to not having a 3D printer, just a method that worked out easier for me. Some sort of projector is necessary to trace the patterns. Or you could print the patterns on transparency sheets and use an overhead projector (if those are still a thing). Or even better, if you had a large scale laser engraver, you could just feed it the files and let it cut them out.

This project took about 2-3 weeks working an hour a few nights a week. Most of the work will be transferring and cutting out the cardboard patterns and hot gluing them. There are 6 rings of cardboard to form the shape, then 20 pieces of cardboard that form the outer shell (more on that on the next step). Then its just adding the details and painting it all.

The original 3D model was not made by myself but modified from one i found on Thingiverse by 7777773. I cut this model up and redid some of the rings to exclude facial details, which was easier to complete after making the shell.

Feel free to contact me or comment for any help you need on this project, would be happy to help. Hope you enjoy making this!


Cardboard (got large sheets for free from work, can find outside large stores too)
Xacto knife
Hot glue
Paper/wood glue (coating the shell after assembled)
Paint (brown, red, white, and black)
Projector (digital or overhead if want to print the patterns on transparency paper)
Tape (to seal gaps in between shell pieces)
3D printer (optional, if want to print attached files for the eyes, teeth, eyebrows, and tongue)

Step 1: Trace Patterns for Rings and Shell Pieces Onto Cardboard

This is a document heavy step so it helps to watch the YouTube video of the 3d file to see a walkthrough on how this thing will come together!

Basically there are 6 rings that are spaced 4" apart that make up the form of the Goomba. These rings are all numbered in the attached pdf files. The rings also have the numbers 1 and 20 on sections of the rings. These numbers are for locating the numbered shell pieces that will cover this form. The 20 cardboard shell pieces get glued to the rings to form the exterior of the Goomba.

So, first you need to download all the ring pdf files and all the shell pdf files. These files will need to projected onto the cardboard sheets and traced, so lets start with the ring files. When doing tracing the outer shell pieces, make sure the "grain" or corrugation direction of the cardboard is running perpendicular to the length of the shell piece (since it will curve a lot in the vertical direction it helps to have the curve so that the cardboard folds along the grain), if that makes sense. Cardboard folds easier when the fold is matching the corrugated direction. Also note that the projections show the tops of the rings so orient them with the side you traced facing upwards. The shell pieces show the exterior face so the side of the cardboard you trace will face outwards and be the outside of the Goomba.

The files have dimensions/measurements on them so what I did was to draw rectangles of those dimensions onto the cardboard and project so that the pdfs fit into them at the right scale (see picture). The rings have little dimensioning marks showing the boundaries but the rings are also dimensioned so that the edges of the rings will fit in the rectangle you draw. The shell pieces are in boxes i drew in the modeling program, so just draw rectangles that size on the cardboard and project the shell pieces so that the exterior rectangle lines of the file line up with the one you drew on the cardboard.

The files also have either 3"x3" or 5"x5" registration boxes to make sure the scale is correct (see picture).


Project and draw all 6 rings and 20 shell pieces onto cardboard. After that is done, you are ready to start cutting all the pieces out with the Xacto knife. The next step is assembling...

Step 2: Assembling the Cut Out Pieces

I will describe the way I assembled this but if you find a better way feel free to go for it!

I realized that I needed to create a general form and not glue all the pieces in order. I first hot glued some 4" tall cardboard boxes to space the rings out, since they are designed to be 4" apart in the 3D model. I then started with 4-5 shell pieces spread evenly throughout the circle (I used shells #1,6,11, and 16) to hot glue the rings into place and build the form. When fitting the shell pieces on it helps to fold the pieces in the direction they will have to curve beforehand. Use a table leg and pull the shells along it to curve it in the long direction (top to bottom curve) then use your hands to bend it to form the curve of the exterior circumference (side to side curve)

The first picture shows the 4" cardboard boxes I made holding the 2nd layer 4" above the first layer. I then hot glued the respective shell pieces to the rings using the numbered sections to connect the 1st and 2nd ring layers. Move the 4" boxes up to correctly distance the 3rd ring in relation to the 2nd and then glue those 4 shell pieces to secure ring 3. Continue this all the way up to ring 6.

*(in the picture you can see that I glued ring 6 before ring 5 to make sure everything was lining up ok. It might be beneficial to connect ring 1 to ring 6 before doing the other pieces so the positioning of the rings line up more naturally than the way I did it. Just make sure if you do it this way, that you will be able to slip the rings inside from the bottom, or use only 2-3 shell pieces to attach rings so you can slide the rings in from a side)

After the rings are all spaced out and have a basic form, continue to glue the shell pieces into their respective places indicated by the numbering used when the patterns were traced. There will probably be gaps but dont worry about those now, we will fix them in the next step.

Congratulations, now we have the external shell of the Goomba!

Step 3: Filling Gaps to Smooth Surface and Figuring Out the Facial Details

So now is time to figure out the position and size of the facial details. Use the Goomba 3D model picture from the 1st page of this Instructable and project it onto your model. Line the projected image and your cardboard Goomba up as close as you can (might not be perfect since youre projecting a 2D image onto a 3D surface). Now trace the facial details onto the Goomba (note that the pupils from the 3D model are more circular than the oval pupils I went with, which are closer to the Google images of Goombas). The pupils are irrelevant to trace if they are going to be 3D printed. These next few steps are going to be a bit more intuitive to each person's interpretation of the features and how you want to proceed. So there is no cut and dry right or wrong way here, or specific sizing of the features.

Now you can cut out the mouth and eye holes.
****SAVE the eye pieces you cut out of the shell for doing the eyes later. You can use the cut out part to trace and make a solid sheet for the back (white) part of the eyes when they get recessed.

There are probably a lot of gaps in between pieces right now. I got some cardboard packing tape (brown) and went over all the seams to make the surfaces join better, especially where you just made the cuts for the eyes and mouth. You can use whatever tape you would like, just make sure it is flexible enough to not ripple too much (like duck tape would). I would have loved to leave the Goomba the brown color of the cardboard to show how it was put together and to highlight the cardboard qualities, so if going this route, brown tape would be nice.

After the tape was all on, I used some cheap 1" brushes from harbor freight and painted wood glue over the whole exterior to give the cardboard a little protection and shell-like quality and, more importantly, to keep the tape from lifting up.

Step 4: Making the Eyes and Mouth

Ok, so like I have said before, this is where you will have to make the best decisions on how to proceed with making the eyes and mouth parts. I will show you the best i can what I did, but the method is very freeform. We are just trying to recess the eyes for some depth and the mouth to put the tongue and teeth in later.

If you want to skip this part and just paint the details onto the shell now, that would be great too and I commend you for making it to this step. You could always just paint the eyes and do a simple recessed mouth. All up to you.

So....the eye pieces we cut out and SAVED in the previous step. Yes, we need to trace those onto a new piece of cardboard to use for the recessed part. After you have those, cut into the support rings about 1" wherever that flat piece of eye will lay (see interior picture). Then hot glue that flat piece into the recesses of the rings you just cut out, hot glued to the rings. Measure how much depth there is between that flat piece and the surface of the shell. If its around the 1" you cut into the rings, use about a 1" strip of cardboard and glue that around the socket of the eye to connect the shell of the Goomba to the flat recessed eye part (see 1st picture).

Now the mouth is next. I just got scrap cardboard and inserted it into the mouth to trace the outside edge/curve of the mouth. Then I cut that curve so it matched the mouth edge and led back about 3" to a rectangular and flat end (see picture since this step was so freeform). I did the same for the top edge of the mouth and then cut a shape similar to the mouth opening to connect the top mouth shape and bottom mouth shape together. Then i just winged the side pieces with small pieces of cardboard and hot gluing the holes up.

If there is any ever overhanging cardboard jutting out, feel free to shave it flush with the Xacto.

There, now the eyes and mouth are done!

Step 5: Facial Details and 3D Printing Them

Attached are all the .stl files needed to 3D print the facial features: pupils, teeth, brows (2 parts), and tongue. My son wanted the brows removable so I built some threaded rods into them to screw them on and off the model. Otherwise just position the brows and make smaller holes where the rods are and shove them through the Goomba to help connect the brows to the Goomba. All the files are to scale, so if your Goomba was made with the same dimensions, everything should work out fine. I printed these as quick as possible so at the maximum layer height (.4mm) in Cura. Definitely helps to use support on the brows and thicken the walls up so bolts dont break off. The pupils and tongue and teeth are simple prints.

After all the pieces are printed then you can paint the tongue and eyes (and teeth if you didnt print them with white filament). The eyebrows are large so there are 2 pieces for each brow, just epoxy them together and secure with tape while it cures (or hold in place for 10 mins while the epoxy cures). Then paint them black.

I had to cut away 2 recesses in the Goomba shell for the teeth to sit flush on the mouth bottom piece.

Now you can paint the Goomba brown if you want (or leave it the color of cardboard), paint the eyes white, spray paint the mouth black, and hot glue all the facial features on.

Step 6: All Done

You've made it! Hope you enjoy your new cardboard, relatively cheap to produce Goomba costume! The last thing I need to do is to make straps so my son can wear this on his shoulders to keep his hands free in case he trips and falls.

Feel free to ask for any help on this project.

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