Many mokuhanga (Japanese technique woodcut) printers are using an L-shaped kento registration jig. This is so each block can be carved without registration kento and a corner pushed into the L-shaped jig during printing. One disadvantage of this method is that the block and jig can easily shift during handling and printing so registration is insecure.
By wedging the block into a somewhat fancier jig, the block is held securely without shifting and the jig can be made so that the printing surface of the block is higher than the jig while the kento are on level with the printing surface. This allows very tight and certain registration and very clean margins without having to handle the damp block between printings.
I made a couple of prints using this jig, an aizuri-e of clover and a sumi-e of blades of grass.