The c9kinetic Projector is a unique and compact toy that demonstrates the principles of compliant spring designs. It is capable of launching small plastic projectiles using the elastic energy stored in a specially designed compliant spring. The mechanism is powered by a 1-piece, 2-stage, 2-layer spring, which allows for a compact and less flat design inspired by the well-known BYU "One-Piece Compliant Mechanism Disk Launcher."

For more on compliant mechanisms, check out BYU's resources. https://compliantmechanisms.byu.edu/maker-resources

This toy is entirely 3D printed and uses a snap-together assembly—no hardware, fasteners, or adhesives are needed.

The spring is "charged" (compressed) by rotating the barrel 90 degrees, allowing you to load a small projectile into the back of the barrel. The barrel stays in place thanks to a compliant locking system on top of the c9kinetic, which can be released by gently pulling back on the lock with your thumb. When the barrel is rotated back down, the system automatically re-locks.

Additionally, the grip is foldable, allowing you to reduce the overall size of the c9kinetic Projector for convenient storage.

Print Settings

I recommend printing the spring in PETG with 100% infill, the other parts can all be PLA with 4 walls, 40% infill. The projectiles will benefit slightly from a 100% infill as well.

For the best results, I suggest the following: Material = PLA / PETG Nozzle = 0.4mm Layer Height = 0.2mm Line Width = 0.4mm Wall Count = 4 (1.6mm) Top and Bottom Layer Count = 5 Detect Thin Walls = ON Wall Generator = Arachne Ironing = OFF (not needed) Support = All required support is designed into this product
Material and Infill: 301 Sping: PETG, 100% infill Projectiles: PLA, 100% infill All other parts: PLA, 40% infill, cubic

Print Orientation: As per STL/3MF files

Related Links

BYU “One-Piece Compliant Mechanism Disk Launcher” https://compliantmechanisms.byu.edu/maker-resources

Visit my blog for more details and other designs: https://www.logicalplanet.com/

Revisions and Updates

I occasionally update and revise my designs. When I do, I’ll document the changes here. Check back periodically for the latest revision notes or if you’re experiencing any issues with a model.

2025-03-14 15:26 PST; the original files I uploaded for the two sides of the c9kinetic did not have the text embedded properly. They are fine to use but I have uploaded fixed versions labelled 101b and 102b.

2025-03-18 13:11 PST; I have had a few people report the posts in the frame breaking when rotating the barrel. I suspect this is either a) a wall strength issue or b) the posts are too tight. To address "a" please ensure you are using my recommended print settings. And, to address "b" the post tightness, I have uploaded two alternative barrel designs. These two new barrels have slightly larger holes for the pivot points. The original design has 6.0mm holes, and the two new ones have 6.2mm and 6.4mm holes. They are indicated as 062 and 064 respectively. Please try them if you have had this issue, and please let me know if it helps.

2025-03-19 09:43 PST; I have modified the sides to increase the strength of the barrel pivot posts. Their outside diameter remains the same but the post will be stronger because of internal design changes. These new sides are version 1v00c.