The rack arrived flat-packed, which I did not expect, and I spent a Sunday turning a pile of steel into something that holds servers. A 24U on castors, second-hand, smelling faintly of someone else's datacentre. It now lives in the garage, which felt clever right up until the first cold night.
The regret, briefly: the garage is unheated, so condensation is a real thing now. The kit runs warm enough to keep itself dry, but I have a hygrometer in there and I check it more than I'd like to admit. The other regret is noise. Even with quieter fans, a populated rack two metres from the car is not silent, and the door does nothing to stop it.
What I'd do differently? Buy the rack first and size the kit to it, not the other way round. I have a half-depth switch wedged into a full-depth rack with cage nuts I'll never get back. Still, it's mine, it's tidy, and I no longer have a UPS balanced on a stack of paperbacks. Small wins.