I've made paddock boots. They are dead easy. Go to the central market where they sell whole lambskins. Work out what size the boots need to be by cutting up an old sheet or some such, and putting it around the leg. Cut the lambskin to the size, hand sow on 2 or 3 strips of Velcro, which you buy at Spotlight by the metre. Woolly side against the horse, skin side out. Slap some oil on the skin side, You can hand wash them if needed and they will dry a little stiff and all you have to do is give them a bit of a rub with your hands and they come up good as new.
I've also made lambskin bell boots when my horse had ringbone and I needed to keep his fetlocks warm in winter for him to be flexible and happy.
As I'm a really lousy sewer and I had no trouble making these anyone could