Horologist

Something like this? You could feed one of those mechanisms into a standard ball pump for both a low input and the advantages of a ball pump.

Great model, love the passive gripper and brick-feeding systems!

Interesting concept, but wouldn't the reduction be greater if the carrier was static and the 28t gear was the output? (12/24)*(8/28) is 1/7.

Great model, it fixed most of the flaws of the previous one. It also looks a lot cooler . I can't shake the feeling that there's a simpler way to do it with a differential, though... perhaps something like this would work? I don't have the parts to build it irl, but the concept seems to be there.

Very interesting. Reminds me of the recent experiments by Yoshihito Isogawa (i.e. https://www.youtube.com/watch?v=ZIRd7-Vgos0)

It has a 3D model on Mecabricks, if that would help: https://mecabricks.com/models/Lkj9J03kvAp

This is a working model of a steam engine that runs on air. The input port is on the top and the exhaust ports are on either side. Airflow inside the engine when the piston is expanding (rendered using mecabricks)... ... and when it's retracting. The piston and valve are about 135 degrees out of phase on the crankshaft (90 would be better). Although it is by no means airtight, with high enough flow rates the leaks become negligible.

Great model! I assume the front wheel is freely hinged with a positive castor angle to get that amount of stability.

Perhaps you could use something different to write with. It looks like your pencil is hexagonal, a round pencil might work better. You could also use a felt-tip pen or fine marker instead of a pencil to reduce the friction against the paper.

Great boat! Love the classic powerboat tilt. How much do the custom props help with the speed?

Interesting idea and good implementation. It looks like the motor stalls every time it changes gears. Could that be avoided with a clutch gear?

Great module! Those slide pieces are perfect for an Archimedes screw.

Great idea, I have one question: If only the bevels are meshing, then wouldn't the 12T gears feel a force pushing them apart along their axles when rotating?

Really interesting walking mechanism! I've never seen anything like it before.

When I made a snowmobile, I found it helped to add small fins (i.e. 30413) to the bottom of the skis to improve steering authority. I also added camber, like on a real snowmobile, but I'm not sure how much of an effect it had on the steering.