The iFixit Pro Magnetic project mat is a clever little tool that helps lay out assembly & disassembly projects. I've made my own share of hacks to accomplish this same task, and the Pro Magnetic project mat would have made those jobs *much* easier.
Fabrication & Assembly.
Wera's Zyklop Premium 1/4" drive ratchet set is a super convenient kit, and like many German hand tools it's a lot nicer than the generic (or even primo) American tools. Having a 1/4" ratchet with a pivoting head is especially good for fitting in tight spaces, and the Zyklop Premium set also includes a variety of screwdriver, Torx, & hex bits - making it totally useful as a general purpose driving tool.
The iFixit Pro Tech toolkit is an excellent do-all electronics repair & assembly set, and should be the starting point for anyone looking to, say, replace a sticky butterfly keyboard or (as I had to recently) drill out a headphone port without also drilling out the computer's audio board right behind it.
The Shaper Origin [note, Shaper is a sponsor of The Prepared] is a pretty rad tool, allowing you to bring 3D CAD into woodwork in a way that's really unusual. I used a Shaper on both rough and finish jobs this year, and in both cases it reduced work and improved outcomes.
Wera's multicolor Hex + L-keys aren't our pick for pure aestheticism (that honor remains with PB Swiss), but with their unique profile they're kind of the next best thing to a Torx wrench and are arguably superior to any other L-key set on the market.
Ballistol tool wipes are great at all-purpose cleaning & rust prevention, extending the life of anything that might otherwise corrode. We especially like their individual packaging; rarely do we need more than one at a time.