Supfire X6 -> 26mm 2.1-2.4 Amp ATtiny 13a Based Buck Driver?

I have inquired from Richard around 26mm MTN-Max PCBs. He agreed, but Its going to take some time he says, which is fine. In the meantime I’m inquiring on the above… I’m looking for a ATtiny 13 based buck driver (8.4v input) doing 2.1-2.4 amps with which I can drive XP-E2s in a SupFire X6. The driver size is 26mm. I’d prefer 26mm for proper heat transfer.

Any ideas?