Update: paid $140 for a Park Tool spoke tension meter, my finger and a cheap wrench were doing the same job
Wheels I built by feel have stayed true for two seasons, the meter just told me what my hand already knew. The shop guys who swear by it say I'm asking for trouble on carbon rims though. Any of you build without one, or did I actually waste the cash?
I bought the Park Tool TM-1 about six years ago after building maybe 15 wheelsets by feel, and honestly I use it maybe once per build now. What it actually helped with was learning what proper tension feels like in the first place, so now my hands are calibrated and the meter mostly just confirms it. The carbon rim thing is real though, those rims can crack or deform way before you feel anything wrong through the spoke wrench. On alloy I'd say you're fine, but for carbon I'd swallow the pride and check with the meter at least at the end. The cash isn't wasted, it's more like insurance you only cash in on the sketchy builds. Two seasons true is a good sign your hands know what they're doing.