Thanks! I don't really know what I'm doing.
What's your use goal? I'm not sure what units you've used, but there's a definitely a visible difference between the Delta printers it looks like you're tooling around with and, say, a 3D45. Not that there's anything wrong with that, especially considering price point - I'm just curious what your usage is.
I was thinking of the sort of middle to lower tier builds I see on reprap.org where people are building for hobbiest or home use, and running $15 rolls of PLA through it.
Right now, I have a secondhand i3 clone with a cracked acrylic frame, worn out bushings, and zip-tie secured linear rails. Objectively, it is a steaming pile but it works ok. The belt pulleys on it don't even have bearings, they just rotate on a screw. The z axis lead screws wobble all over the place. On the one hand, improving on it should be pretty easy. On the other hand,the thing already is capable of producing reliable interfaces for my camera's lens mount and hood rings.
I'm still figuring out the best workflow for designing stuff. I've gravitated to mocking the whole thing up roughly in blender, and then fiddling in openscad until it works like mockup.