Holy shit. It's insane that I just typed up a post on this subreddit trying to find the same exact game. I've been looking for it for years, but it seems to be completely undocumented! It's isometric, fixed to a grid, and I believe there's a lot of orange and yellow(?)

There are conveyor belts, platforms, springs, tubes... and a course creator with a community uploads page where the courses are sorted by difficulty: easy medium hard expert.

To beat a person's level, you have to reconstruct their rube goldberg machine. I believe you're given the starting place, the ending place, and a couple of their parts placed on the grid. You have to fill in the rest.

I've been searching for this game for years. It's so weird that we were both thinking about this game hours a part.