SCHNEIDER ELECTRIC Non-Illum Push Button Operator,Green - Non-Illuminated Push Button Operators - 2EN16|9001KR1G - Grainger Industrial Supply
If you want a true 30A switch, something like this is what you are looking for. It needs a surface about 4.5" wide to mount to correctly. Since most mods put the button on the grounding leg rather than the hot leg, the NEC (code for electrical construction), if it applied, would only require it to be rated at 20% of the maximum ampacity of the electrical system. For 30A, you need a 6A switch. That switch I posted yesterday is actually the same one that is in the SIG 150. I have a 2x26650 guitar pedal box mod with the same switch in it. I worried about the ampacity when I got it, so I took the switch apart. The contacts inside look thin, but are roughly the equivalent of a 14AWG copper wire, which is good for 15A... which is in turn good for 75A on the hot leg. Let me plug that into Stem Engine...
That's 315W at 4.2V or a 0.06 Ohm build. That's 1 1/2 wraps of N80 @ 2.5 mm, dual coil. Or half a wrap of 26G KA1 (which is basically a direct short!!!! Lol!).
Even at the switch's rating of 3A, you should still be good down to a 0.28 Ohm build. ( 4.2V and 15A on the hot leg for 63W) That's about 8 wraps of N80 @ 3mm, dual coil. Which is a nice build. Not too hot, very little ramp up, not too hard on your
batteries, decent clouds. As long as the mod is built parallel, not series, and you keep your builds above a quarter ohm, you should be fine with that button.