Another Pi Bumper

Same as the source thing (#629886), this is designed for the Model B.

With the original, I found that the friction-fit pins were
1) Too small, so there was actually no friction - the pieces fell apart easily.
2) Too brittle. Layer adhesion was insufficiently strong to keep the pins from snapping off easily.

To solve these problems, I made pins as separate pieces, so they can be scaled as necessary to provide a friction-fit, and so they can be printed in an orientation more suited to structural integrity.

Note: If you scale up the pins, don't make them longer - only wider. If you increase the length too much, they'll bottom-out in the frame holes.