Compression molded Battle top

INTRODUCING SCRAP-ATTACK! 

Scrap-attack is a battle top designed specifically for the battle top contest here on Printables July 2026. It features a "blade" disk that is made of compression molded printing scraps that you can make with a 3D printed mold. Weighing in at ~17 grams, the blade itself is sure to make this top pack a punch against its competition and keep on swinging. 

Printing 

There are two sets of models for this project. Top part models, and Mold part models. Technically you could print the "blade" disk with like 100% infill and still get a pretty good top, but what fun is that? The compression molded one will be even sturdier so it just may make you win the battle. 

Top parts: 

• Cone - Print this with 4-6 walls, infill should be around 25% probably, though the more you have the more mass your top has so it will spin for longer or with more torque so it is less likely to be knocked out. 

• Cap - This piece is largely aesthetic, but print it with the same settings as the Cone part

• Mag sleds - These are part of the release mechanism for this design, print them at with 2-3 walls and 15% infill. 

• Mag Post - Another piece of the release mechanism, 4-6 walls, 25% infill. Screws go directly into this piece so it should have thicker walls to help with that.

• Launcher handle - 2-3 walls. 15% infill 

• Launcher cap - 2-3 walls. 15% infill

• Thrust bearing - print these Solid. They will bear the forces of a large screw that holds the assembly together, they need strength. I do not recommend PLA, they need to be rigid so something like ABS is preferable. 

• Ripcord - 4-6 walls, 25% infill. This will see mechanical forces directly against a GT belt gear, make it sturdy.

Mold Parts: 

THESE PARTS MUST BE ABS OR PETG, they get hot when you put in the Charge of PLA print scraps. They need to be able to take it.

• Mold top -  4-6 walls, infill should be around 25%

• Mold bottom - 4-6 walls, infill should be around 25%

• Mold ring  - 4-6 walls, infill should be around 25%

Hardware required

ASSEMBLY

Once you have everything printed out, set everything except the mold parts aside. The last piece is the "blade" disk and we need to make it using the compression mold parts. 

STEP 1 - Spray the silicone cup cake cup and the top and bottom molds with mold release. Set them aside

STEP 2 - measure out 17 grams of purge poops, supports, or other bits of 3D printing waste and place it into the silicone cup cake cup. If it is too big to fit inside the cup without hanging over, you'll need to cut it into smaller pieces. The smaller the pieces the more streaks you get in the final result. There is a point of diminishing returns though. So don't go too small, or do it's your top so do what you think will look cool

STEP 3 - Place your silicone cup cake cup with 17g of material into your toaster oven or use your other heat source to begin melting the scraps down. I am only going to detail the toaster oven method because that is what I have. My toaster oven, set to 220C (about 430F) takes about 15-18 minutes to soften PLA to an acceptable level. You will probably wanna do this outside or in a garage with the big door open if you can. The smell of PLA while printing isn't too bad but when you melt a large amount like this it really stinks up the place. PPE if you're gonna stand directly next to it and good airflow if you're not but keep an eye on it either way. I am not liable if your toaster oven or heat source catches fire. 

STEP 5 - While you wait for the material to melt, prep your mold station, place the bottom mold in the center of your work area, place the mold ring onto it. Spray both the top and bottom mold halves with mold release spray if you haven't yet. Place your wood board or block in a convenient place. Just generally get everything all lined up. Once the plastic comes out of the oven the clock starts ticking as it cools down.

STEP 6 - Once your heating is done, put on your silicone baking gloves and carefully remove the cup cake cup with your molten PLA in it. Invert the cup and try to scoop all the material out and roll it into a ball in your gloved hands. Then press it into a disk like shape between your hands. 

STEP 7 - Place the disk of PLA you squished last step onto the center of the bottom mold, then take the top mold and be sure you have aligned the blade tips before placing it into the Mold ring on top of the bottom mold half. Use the wood board or block to apply as firm and even pressure as you can for at least 1 minute. Place a heavy object onto the top of the mold after that and then let it cool in the mold for ~10 minutes

STEP 8 - Time to de-mold! remove the mold ring from the assembly and inspect the seam between the mold lines. Unless you used some sort of mechanical press, you likely will have a very slight gap somewhere along the seam. Use a flat-head screwdriver to gently pry the two halves apart by twisting the screwdriver like a key in a lock. The idea here is to minimize damage to your molds. You can re-use them until they break technically, and the first time you try to mold a part you might not get a perfect part. If that is the case you'll be happier if you don't need to print the parts again and can try again right away. It may take a few tries to get the best possible part. 

STEP 9 - Wait another 10-20 minutes for the part to cool down or give it a splash under running water to cool it the rest of the way down. 

STEP 10 - Clean up. The flashing (the thin, squeezed out material at the edges of the part) can be removed with a pair of side snips and a deburring tool. Save those bits, you can always make another part with them. The holes for the screws that keep the top together must be drilled out. A drill press would work best but if you don't have one just try to make as straight of a hole as possible, the screws just need to go through them so if you make it a little bigger you might be able to get away with it. 

STEP 11 - The center cutout will likely need to be drilled out, I haven't been very successful at getting it so thin that I can just poke it out yet. Drill a couple holes through what remains and if it is thin enough a deburring tool is all you'll need to remove the flashing.  

ASSEMBLY

Now that we have all our parts made, we are ready to assemble! 

STEP 1 - Take the cone part, and screw the M5 x 10mm bolt into the hole on the pointy end. 

STEP 2 - Take the "Blade" Disk and the Cap and place them together. Be sure that the cap is facing with the countersunk holes facing upward, and the blade disk should have the little pockets on the blades facing up. Place an M3 countersunk screw into each of the holes. They will be loose so keep that in mind so you don't lose any. Place an M3 washer on each screw on the bottom of the disk. 

STEP3 - Align the Disk/Cap assembly so the screws line up to the corresponding holes on the Cone and screw them together. I did not design this to need heat set inserts so you can just screw them together. Tolerances on your printer will need to be taken into account to make sure the holes fit but if you're using a good machine like a Prusa or a bambu you likely don't need to. 

STEP 4 - Insert 4 magnets into each mag sled part. You should have three of them. The poles of the magnets facing the center of the top should all be the same. It is a little bit tricky but you should be able to place the mag sled into the center hole of the assembled top, and slide them into place one at a time. Once in place the same poles will repel each other. The sleds should slide around freely. 

STEP 5 - Assemble the Thrust bearings by pressing the rest of the ball bearings into the track on the bottom bearing part. You'll need to do this twice. 

STEP 6 - Assembling the Launcher. Take the Launcher handle and place one of the assembled thrust bearings into the cylinder. it should fit snugly but not so much that it can't spin. Place the bearing cap in on top of it with the smoothest side facing down. 

STEP 7 - Take the launcher cap and place the other Thrust bearing into the deeper hole on the top. Then insert the M5 x 45mm bolt through the thrust bearing so the head rests against the bearing cap. Thread the GT belt gear onto the M5 bolt and push it flush against the launcher cap, tighten the grub screws so it stays in place. 

STEP 8 - Place the assembled launcher Cap onto the Launcher handle. Then insert the three M3 x 12mm socket head screws into the holes and screw the Launcher cap and Launcher handle together. The M5 bolt should stick out of the bottom of the launcher handle a good amount. 

STEP 9 -  Assemble the Mag post by placing two of the magnets into each hole, and screwing the mag post cap onto the post so the magnet holes are covered. Then screw the Mag post onto the M5 bolt on the Launcher assembly. Make sure the M5 bolt can spin freely, if you tighten the post too much you won't be able to launch the top. 

STEP 10 - LET-ER RIP! Your SCRAP-ATTACK top is now finished! insert the ripcord into the hole on the side of the launcher with the teeth facing towards the gear until the ring of the ripcord is all the way up against the launcher. Place the hexagonal Mag post into the corresponding center hexagonal hole of the SCRAP-ATTACK and ensure the Mag sleds stick to the post. They should hold the top onto the launcher with magnetic force, but when you pull the ripcord the top should spin fast enough that the centrifugal forces throw the mag sleds outward and it releases the mag post, allowing the top to drop off of the launcher.