So i've been wanting to design for a simple toy that i can give away to my nephews and nieces during our family holiday.. The toy has to be simple to 3d print and easy for the kids to assemble.. And that will entertain them for while.. And it needs to be 3d printed cheap since i have a lot of nieces and nephews..

So i came out with the idea of a catapult that has to be assembled and all the parts will be laid out kinda flat and connected together like those gundam figurines that you have to assemble.. The assemble will be fairly simple following the instructions given..

And you can pretty much catapult anything small.. but to keep it save for the children to play.. i'm gonna use the foam rubber nerf balls as boulder for the catapult..

Difficulty level:

3D printing - Easy
Assembly - Easy
Wiring - Nope
Painting - Nope - unnecessary

So let's get started..

Supplies

Nerf ball blaster and as always a FDM 3d printer to print all the parts..

And of course a 3d printer - i'm currently 3d printing using BambuLab P1s printer.. you can find them here if you're interested.. these are my affliliate links to buy the printer..

Step 1: Modelling Using Tinkercad

I've design the whole catapult in Tinkercad and split it up into small flat parts that can fit into an A4 size shaped card.. Everything was easy to model except for the springs.. i couldnt get the spiral shape down using tinkercad primitive shapes so i had to design the spiral spring in Inkscape and import it into tinkercad as SVG file..

After the design was finished.. i had to re-arrange the parts to fit into a small rectangular frame card that can be printed on a small 3d printer.. i chose a size smaller than 200mm x 200mm to fit into any small size 3d printer..

I've also include different arrangement of the parts in my tinkercad page.. you can also export whichever you want..

You can find the 3d printed stl files here: https://makerworld.com/en/models/26542

catapult card

Step 2: Assembly - Catapult

Once printed all you have to do is cut the parts away from the frame using a cutter or scissor..

To assemble the catapult all you have to do is follow the video instructions i have provided.. its fairly easy to understand and assemble yourself..

Step 3: Conclussion

I think i spent more time trying to re-arrange the parts to fit the rectangular frame than designing the actual catapult itself.. i wanted it to fit into a small 3d printer so i made the frame below 200mm x 200mm..

Since the catapult card was small.. it could fit into an A5 plastic envelop.. making it easy to package and turn into gifts.