Still finalizing the clip design, will keep you posted.
At this size, not sure another mm or 2 will help much with heat and if it gets beyond 15mm, then we are at CR2 size.
I was hoping for a custom TIR lens but it's extremely expensive to cast from scratch.
Will be going with Aluminuim reflector, for now likely OP, but possibly something like the reflector in the Olight T10.
We need to test the beam pattern, though with a small reflector, it will be floody so not sure there is too much merit in an SMO reflector.