Black friction pin without slots connectors are common in older Technic sets. Note that these were quickly replaced by the current version with slots that is much easier to remove. vs Especially ...
We have a pulley and a bunch of rubber bands: We don't know that part numbers, but they all were part of a Mindstorms (RCX 2.0) set. My son was trying use the pulley and band to transfer power to ...
This blogpost on Technic Bricks briefly explains a few 'brick paradoxes' or dead ends. This particular model seems impossible to disassemble by hand: How can I remove the axle without ...