dpb wrote:

What is often done is rather than just setting the shelf on the pin,
rout a groove on the bottom side of the shelf for the pin to set
in...invisible, no hassle in moving/rearranging and fairly easy to do
w/ a jig/template to cut the slots consistently.

Oh, good call. I'm sure I've seen this on flat-pack furniture before but
it didn't jump to mind. I think a forstner bit is the way to go - easier
to jig and work with than a router.