My latest attempt at organization is a set of storage bins suitable
for CD media in jewel cases; each bin has wood front/back
panel so can go drawer-like in a case, with only wood showing.

To save weight, the sidewalls and bottom of the bins are
of tempered hardboard (we used to call it Masonite). The
sidewalls are glued to the front and back, but the bottom
floats in dadoes in the wood, and tabs on the bottom
engage slots in the sidewalls.

It's all ready for glueup, but two problems arose. First, the
tabs were formed by using a dado blade to nibble most
of the material away (four tabs, each 3/4" long, are
all that's left of the 12" edge). The problem is, it takes
a long time and generates lots of sawdust.

The material is 1/8" thick, so the slot dimension target
is 0.130".

Then, when the time came to make the slots, I found that
my Dremel router with fine endmill blade makes a ragged cut.
The same router, with a rotozip-style steel cutter ALSO
makes a ragged cut, and the length is too great to use conveniently
(maybe with an inch-thick subbase added, it can work).
The true router blade for these cuts doesn't allow starting the
cut blind, so I've stacked and predrilled all the sidewalls.

First question: is there some trick I'm missing to making a
clean cut? The table saw worked OK, but the rotary tooling
is just making a furry mess of an edge.

Second question: how hard is it to make a punch/die to do this
kind of slotmaking? The current batch of bins is just a dozen
or so, but I can see a use for more (in other sizes, too).

Third question: other than a full footwide-throat shear, how
can the edge-with-tabs be made more effectively? I guess
waterjet-cutting is unlikely to fit my budget.