I've been on a MIL-DTL-38999 journey over the last few weeks. There's a lot of surplus tooling on Ebay, and they're by far the best connectors I've ever used. Rugged, really high pin density, and impossible to insert wrong. The prices are high for new tools, but there's tons of surplus floating around thanks to government standards. There's also solder-cup versions of a lot of the connectors so that no crimp tools are required. If you want to use the crimped versions, you'll want the M22520/1 basic tool or M22520/2 miniature tool for smaller wire gauges. You'll also need a positioner to hold the crimp in the right position within the tool (these are interchangeable for a ton of different models). You'll probably want the M22520/1-04 turret head. A Chinese company called JReady sells new crimp tools with the positioners for $300. It sounds like a lot, but it's much less than the $800 American made tool and even less than the single purpose crimp hand tools for cheaper Molex and JST connectors. One tool standard, lots of different high quality connectors!