What are your At-home horse must-haves

I'm going to be acquiring a mini soon (I've posted once before- he's coming from a relative who isn't caring for him adequately), I'm not new to horses, but I haven't had a horse for about ten years- and I've never had one at home, I've always boarded, so I'm trying to make sure I have all the necessities thought of to avoid the late-night emergency run to the store.

He'll be in a pasture with an attached stall/run-in shed, no actual barn. And after he's gelded I am going to see about getting him a companion, since a solo horse is obviously not ideal.