I bought a santoku knife. It is nice. Then my wife said, "where are we going to store it to stay safe?" 

Definitely not in the “gear drawer”, this thing was pricey. So I made this to mount on the top of the current butcherblock. It nicely fits both the 7" santoku knife as well as the 8" chef's knife.

I stuck it on using double sided tape. Commitment is hard.

Mine is printed in wood filled pla, though it doesn't actually match the wood of the block. Smelled nice while printing, though.

I suggest printing with the knife cavity on top and you likely only need supports for one of the edges. There's no reason to not go with a thick layer height and you can likely go very low on the infill with an extra wall layer or so and make sure the non-knife-side has enough layers that it doesn't get the “low infill warble” effect.