If you can't find a MOSFET big enough

And you spent too much time watching it :-)

Reminds me of an article in Popular Electronics half a century ago. It announced a new 1000-watt (or was it 10kW?) transistor with a photo showing a TO-3 style case alongside a wrench that looked tiny by comparison. Probably the April issue.

That's crazy, but the guy probably enjoyed it. The FR4 adds a huge thermal resistance. And those dinky leads and traces won't be happy at

Just buy one of these:

or put a few smaller fets around a heat sink, to spread out the hot spots.

Someone finally found a use for a 555.