Here are the most important items for a leather repair kit. A lot of my own leather repair work involves replacing broken snaps and buckles. Many leather repair kits come with a sponge, lambskin stain applicator, or microfiber applicator. Leather PiecesSome kits include small pieces of leather for patches for tears or worn-out areas. Most belt blanks and belt leather are around 8 or 9 ounces in thickness and come undyed.