The main issue with the original prototype (besides being ugly) was the lack of a battery. To resolve this, version 2 is designed around a power path that uses a TP4056 LiPo charging module and a 800mAh+ single cell LiPo battery. [Andreas Speiss] has an excellent review of power options for ESP32 projects, and highlights the key challenge with the ESP32 modules: the not-so-LDO voltage regulator (AMS1117). The 1V dropout at higher currents means that using it directly with a 3.7V LiPo will not provide enough voltage to the ESP32. Rather than the HT7333 suggested by [Andreas Speiss], I ended up using the AP2114 because it was available - note that the "H" package is pin compatible with the AMS1117, but those weren't available, so I used the "HA" package, requiring some additional jumper wires (and makes this a legitimate HaD project in the process). After all of that (and a case re-design to fix the aforementioned "ugly" problem), the updated laser timing gate can now be powered off of a battery or 5V micro-USB.

The second version also features some mechanical upgrades in the case design. My recent discovery of knurled inserts has improved the mechanical side substantially. They make assembly much easier (no more captive nuts or deep countersinks for printed stand-offs) and the final result more robust. A 1/4"-20 insert also works very well for tripod mounts: while tripods can have non-standard shoe sizes (as I found out previously), they almost all have a 1/4"-20 screw to connect to your hardware. Finally, I invested in a couple of kits for making JST & DuPont connectors, which also made prototyping and final assembly much more straightforward.