Ralph’s three rules
Try and do as much of a build as you can. You’ll pick up new skills , and save yourself a few quid. If it really isn’t possible, then you can tap into the skills/knowledge of a specialist.
If If you do need to farm out certain parts of a project out to specialists, be realistic about how long they will take. It’s often a lot longer than you first anticipate…
Measure once, measure twice, then measure again. If you’re fabricating parts, or mating one to another, fit is absolutely critical. “That’ll do”, simply won’t do.