I made the bottom out of a scrap of cherry. I made 1/4″ grooves and the plywood I have on hand is, of course, too small for those grooves.
Then I glued up the drawer after a bit of finishing with my smoother. I’ll open up the clamps later today and see how it fits.
sheworkswood.com 
I just ordered that Veritas hold down. What do you think of it?
It's great! The kind you beat in are good also, but they have a tendency to move the hold down piece when you whack it. Not the Veritas hold down.