I had some upgrade ideas for a couple of towers that are still missing them (but if you don't need them then that's fine)
The first for disco ball is called disco inferno. Instead of stunning once for 5 seconds, it stuns 4 times consecutive times for 2 seconds, which allows it to stun any exterminators you missed on the first interval. It also lightly burns any enemies caught on the first stun
the second for toy factory is called demolition factory. You can tap on it to spend some scrap and summon a nuclear vroomba. it deals big damage on a 3x3 area upon death just like the og nuclear vroomba, but the demolition factory also has a big cooldown once used