3D Printed Wrist Shooter

Hello, my name is Calvin, a student in Ms. Berbawy's Principles of Engineering class. For my SIDE project, I decided to make my own 3d printed wrist rubber band shooter. Feel free to check out other amazing projects her students have made here.

What Is It?

For my SIDE project, I decided to create a 3D printed wrist shooter that shoots out rubber bands with a range from 14-20 feet (depends on the type of rubber bands). I was inspired by the design of the web shooter from Spider-man and the "P604 Catch" rubber band shooter. By integrating certain aspects of both, I was able to create a rubber band wrist shooter, that not only has a very simple and unique design but is also appropriate and playable for most kids.

Although this wrist shooter may be somewhat inaccurate, it is completely disproportionate to the amount of fun this will give you just from playing with it!

My build is designed to be assembled by parts. You can also use any computer-aided design (CAD) software like Fusion 360 and Onshape to create your own parts or to modify mine.

• 3D Printer (Prusa Mini +)
• CAD Software (Fusion 360 or OnShape)
• 3D Printing Filament (PLA)
• Slicing Software (PrusaSlicer)
• Rubber Bands (What I used)
• Sandpaper (What I used)

Optional

• Superglue
• Any cutting tools (Switchblade)

Download all the attached STL files

My project is assembled with 5 parts.

Part 1 (Light Blue) is basically the base of my entire project. It has a circular rest with enough space to fit my hand and write through. On the top side, I cut out the edge of the 10 mm cube with my switchblade in order to insert a 10 mm cube into a 10 mm cubed hole from another part to make it easier to assemble.

Parts 2 (Gray) and 3 (Blue) share a very similar design. But unlike part 3, part 2 has a 10 mm cube extruded from it to connect to part 1. Both parts 2 and 3 are designed as a shell for part 4 (Green). As shown in the photo, part 2 (Gray) has its own cylinder-shaped extrusion while part 3 doesn't. This cylinder fits through the hole from part 4 (Green).

Part 4 (Green) is the trigger of the wrist shooter and has two holes. The hole at the top fits perfectly with the cylinder-shaped extrusion from part 2. The hole at the bottom is where rubber bands will be wrapped to be used as a "trigger resistor" for the wrist shooter. The top of the trigger is where the rubber band will be loaded. The loaded rubber bands will be stretched to Part 5 (Orange)

*Trigger resistor - When a rubber band is stretched and hooked onto Part 5 (orange), every time someone pulls the trigger, the rubber bands attached to the trigger resistor will pull the trigger back to its original place so that it can be pulled again.

Part 5 (Orange) is an extension to stretch the loaded rubber band even further. I included a hook at the bottom of the part to hang the rubber band that is stretched from the trigger resistor. In order for the shooter to be loaded with a rubber band, I designed a slit at the end of part 5 for the rubber band coming from the top of the trigger to stretch to.

• Once all the STL files are downloaded, I opened up PrusaSlicer (you should use the slicer suited for your printer).
• Once I got my slicer open, I added my STL files and arranged them in such a way that the print would have the lowest chance of failure.
• I sliced the 3D models with a 30% infill. When I tried printing my models at 20% infill, there were many times where smaller parts of my model would break apart. So to make it stronger, I had to increase its density.
• I also enabled supports (touching build plate) since Parts 2, 3, and 5 have overhangs.
• Then I started printing on the Prusa Mini + with PLA filament (filament I used)

Once all of my prints were done, I removed all of the supports. I recommend using sandpaper to smooth out the edges out especially around the overhangs, holes, and other areas where there were a lot of supports.

1. To assemble all 5 parts of the wrist shooter, I connected the cylinder-shaped hole in the middle of part 4 with another cylinder-shaped extrusion from part 2.

2. Once part 4 was connected to part 2, I connected it to part 3 using the two cylinder-shaped holes I made on part 2.

3. Next, (while assembled) I connected part 2 to part 1 using the 10 mm cube-shaped connection points I made.

4. Once parts 1 to 4 are all assembled, I used the hole made from parts 2 & 3 to connect to the extrusion from part 5.

5. Now that all 5 parts are assembled, to make the trigger resistor, I tied the rubber band to the bottom hole of part 4 and stretched it to the hook from part 5.

Challenges
Assembling and disassembling the 3D prints was fairly challenging for me, mainly because of the connection points. Each time I tried to assemble or disassemble the parts, they snapped. If any of the connection points do not fit, feel free to use any cutting tools to trim down the edges of the extrusions so that it is easier to assemble. If you plan on keeping your model assembled, make sure to use super glue at the connection points.

To use my assembled Wrist Shooter, I first took my rubber band and stretched it from the top of part 4 (trigger) to the slit at the end of part 5. To use this Wrist Shooter, I slid my arm through the wrist rest far enough where my index finger can reach part 4 (trigger). Once my rubber band was loaded and the trigger resistor was ready, I pulled the trigger to shoot the rubber band.

To test the accuracy of my shooter, I also printed the STL file of Knockable Target (attached).

*NOTE: When I first printed this Knockable Target, it was very tiny. So before you print, I recommend scaling the model by 150%.

Although it was a challenging project for me, I had a lot of fun working on it and I feel that the result was great. Thank you for reading my Instructable!