My "garage" was just a roof supported on posts when we moved in. I built walls from pallets, which I always have plenty of on hand. Covered them with re-claimed tar paper...all four walls were slapped together and made
water tight in a day and a half at zero cost. Garage is full of tool shelves made from....pallets of course.
Our
chicken run at our old house was made mostly from pallets.
Quarried stone is sometimes shipped on pallets: around here their always oak pallets, so you get good lumber that way.
I have never gotten very fancy with my pallet building....if I'm gonna go all out for a building
project, my hands would rather work with branches. I like natural materials and am happier working with them. Just a matter of preference. When I need a flat surface, I'll very patiently rip some natural edge boards from a log--with my chainsaw. Pallets, I've only ever used for quick and dirty projects. You can of course make great stuff with pallets--I just have never applied my patience in that direction.
Now the oak pallets are impossible to dismantle--unless the wood is fresh and blonde. The older grey ones, forget about it. Since I know I won't make anything great with them, I'll take apart the blonde ones and give the material away to someone who loves that kind of thing.