This block has space for 16 small chisels. Most slots extend 3" deep into the block. The dimensions of the opening vary. This allows different sized chisels to set into the block and remain vertical.
Two slots however have very unique internal shapes to hold short curved blades. These are the two slots which are perpendicular to the rest of the slots: See the two chisels in the picture; the two slots support those two blade sizes.
On the one hand, the blades themselves are not visible. On the other hand, my simple holes-in-a-2x4-block holder obscured the blades too.
The author marked this model as their own original creation.