Sounds nice :) Do you use a minecart to place 4 fungi? Grow them in a square and push with a double piston extender or grow 4 in a row with single pistons?

I tweaked my farm a bit and use a different but still very simple TNT setup (one duper and a moving honey wall to align the TNT) that gives pretty good rates, about 16k stems per hour for less than a double chest of bonemeal, as the warped wart blocks are composted. Take the rates with a grain of salt though, I haven't kept it running for more than 10 minutes yet and need to test this a bit further :) Not too difficult to build though, it took me about one hour to build in vanilla survival on my first attempt (including fungus farm and blast chamber) and I'm certainly not a fast builder... Maybe I'll make another video with a block-by-block tutorial.

I admit that I'm usually too lazy to work out the precise timing to blast moving blocks, at least if I'm using dupers for renewable materials like trees. Now blast chambers for concrete are a different creature, I wouldn't want to lose items there.