What did you do to your trains today?

I've now found and acquired a power bank of the exact type I planned to use for the 5V smoking locomotive, complete with its own cable. I didn't know its measurements when I built the tender chassis, but the length and width are just right for the base. Even the walls I prepared are only a little taller. Since it won't be a permanent installation, I'll no longer have to repeat the dumb mistake of using my laptop as a 5V power source. One time when I tested the same engine, all my USB ports were unfortunately ruined forever. It could essentially fit into any other train or building that would require 5V for whatever reason. The fact it's rechargeable also defeats the purpose of buying more than one unit, unlike most dedicated batteries. That said, I will have to keep its original cable intact and find another old USB plug (not the "ex-charger" I use for testing/jumpstarting).

Update: it seems I won't be able to use the whole power bank (shell and circuit) the way I thought I could. Even after a full charge, the thing refuses to power a motor, LED or heating element through the 5V (USB) output. It's also not very good at charging a smartphone, which is what it's designed to do. However, taking the bottom off revealed a single 18650 battery (unmarked, possibly 3.7V) that can be removed like any other cell, without any wires or anything besides the charging circuit. That alone can do anything the circuit prevents it from doing, so my only real use for the power bank is to recharge the cell if needed.