can't make a loot table for a custom storage block

so i made a custom storage block (a shelf with 12 slots for items) that spawns in a structure i'm making, and i want it to have it's own loot table similar to a chest. the problem is i don't know how to make a custom loot table for it and i can't find a solution anywhere. is there a way to fix this or will i just have to resort to using chests?