In this Instructable, I will teach you how to make a fully functional butterfly knife replica made from cardboard! Skepical? Click on the GIF above! This knife looks totally AWESOME and can be made under $6!!! What are you waiting for?! Go grab some cardboard!
Step 1: The Invention of Cardboard-Ply
Cardboard-Ply...basically plywood made from cardboard. Ply-wood is made by stacking thin pieces of wood, usually three or more, and sticking them together with some kind of adhesive. Usually, cardboard is given thickness and strengthen through a corrugation method. The only problem of using corrugated cardboard is that a lot of empty space is left between each layer. This decreases the stability, weight, and durability of the end product. We are going to create our Cardboard-Ply using cereal boxes, wood glue, and a lot of pressure.
Step 2: Cutting, Gluing And...Pressuring?
Cut out six 5"x 8" pieces of cardboard (from your cereal boxes that always get thrown away). Apply a thick layer of wood glue between each piece of cardboard (excess glue will get squeezed out in the final step). Stick all six pieces of cardboard together and put a layer of wax paper on top of and underneath your cardboard-ply. This prevents sticking and reduces the cleanup. Next, stack a lot of HEAVY STUFF on top. I literally put three heavy books and a really heavy chair on top. Leave it to dry for about 8-24 hours.
Step 3: Knife Replica Sketches
I decided to replicate the CSGO Balisong knife. Using reference images, I sketched the outline of each component onto a piece of graph paper. You can either find a knife of your own to replicate or use the sketches I have uploaded below. I used a cardboard template of each component to make tracing easier.
Trace these pieces onto the cardboard-ply
- 4 full handles (front and back for the 2 handles)
- 2 partial bottoms (goes between the handle front and back)
- The blade
Step 4: Cutting the Cardboard-Ply
Use whatever tools you need to cut the cardboard-ply. I used a Dremel to rough cut the shape of butterfly knife, then precision sanded it. You will be impressed by how much the cardboard-ply actually feels, sands, and cuts like wood!
Step 5: Gluing the Handles Together
Apply glue to the bottom pieces of the handle and adhere them between two handle pieces. Use clips to clamp the bottom ends of the handles. Let them dry until completely dry.
Step 6: Rough Sand and Drilling Holes
Rough sand the handles using 60-120 grit sand paper. Make sure that the handles almost seamlessly correspond with each other no matter which edge is touching which (they reverse when you open the blade). Drill the holes in the top of the handle (where the axle will go).
Step 7: Thinning the Blade and Drilling Holes
Thin the blade until you can smoothly slide it between the handles without getting the edges caught (sand off about 2 mm off of each side of the blade). Pencil in the line where the blade starts to sharpen. Use a Dremel to sharpen the blade’s edge. You will start to see some wear and tear on the face of the cardboard. Don’t worry, we will fix that in the next step. Drill the holes in the blade where the axles go, as well as where the lock dowels go (refer to the image of the diagram in Step 3 for clarity).
Step 8: Hardening With Super Glue
Use a liquid super glue to coat the cardboard. The cardboard should soak up the super glue. This hardens the outside of the butterfly knife and makes it easier to sand. Wait for the super glue to dry completely, then smooth sand the handles and the blade.
Step 9: Spray Paint
Spray paint the butterfly knife with your desired color. Keep in mind that painting adds layers, so try not to spray to many layers on the blade. You still want it to fit between the handles right?
Step 10: Decor and Touchups!
You can choose to decorate your butterfly knife any way you want but I think that using aluminum tape looks really cool!
Step 11: Assembly!
Cut out 4 cardboard “washers” (basically a circle with a hole in the middle). These will go on either side of the blade axle to make rotation smoother (refer to the pictures). Insert the wooden dowels, super glue them, then snip off the excess length. You can color the dowels black to make them blend in. Cut 2 half inch dowels and glue them into the remaining 2 holes (these are the locking axles).
Step 12: Have Fun With Your DIY Cardboard Butterfly Knife Replica
You're finished! Be proud of your cardboard butterfly knife replica! Surprisingly, it is possible to do simple tricks with this butterfly knife replica. I’m not very experienced in the arts of “butterfly knife tricking” but I have to say, it isn’t half bad for a butterfly knife replica.
If you liked this ‘ible, please give it a vote in the Cardboard Contestand comment below!
Until next time,