[elliotf]

Keep at it! Part of the problem is designing, part of the problem is printing. If there's a reprap group or a makerspace nearby where there are people with experience, that would help you a lot.

I've tried to keep my designs as simple as possible and it's worked out alright. As you say, more complex things are fairly hard to model. Having calipers so that I could accurately measure things greatly helped me design things for around the house.