I'm a two for sure!
I just like taking stuff apart, making it better (or worse ;-) ) and putting it back together again!
My lockdown project was a twinset build, using pretty much all second hand parts except where i either couldn't find a part s/h or it made no sense to use a s/h part
A pair or second hand cylinders, bought out of test cheaply, and hydo'd
An ex-display Apeks isolator manifold, much reduced
An second hand Mares XR backplate
Two second hand Scubapro MK25 1st stages, both fully rebuilt
A second hand Apeks MTR octo reg
A (very) second hand Intespiro Aga Full face mask, that someone had used in salt water, failed to wash out, then left. Was bought as "in freeflow" and inspection showed the dv assembly to basically be a corroded pile of scrap. Quick look through the parts books, and i found that the SCBA version of this mask uses most of the same parts, so i bought a very cheap ($20) second hand SCBA mask, and pulled it apart, and yes, the metal bits which were corroded were identical, so a rebuild kit and some o rings later and bingo, one FFM for under $100
The Apeks WTX45 wing is new, because a) it's safety critical and b) most second hand ones are well knackered by the time people want to sell them!
All the hoses and fittings are also new, because new hoses are cheap, and are effectively a service item anyway, and because i wanted exact lengths for tidy hose routing
My next project i think is a DIY WOB machine, to automatically plot respiritory pressure vs flow, including when wet, and at ambient water pressures up to 5 bar........