I don't know where to buy one, but I made my own.
Start with a 1/4" steel plate.
Then you'll need 2 drill bits. Let's say you want 3/8" fluted dowels.
You'll need a 3/8" bit and another that is undersize by twice the desired
depth of the flutes. If you want 1/32" deep flutes then you need a 5/16" bit.
Drill the plate all the way through with the smaller bit. Then drill in the same
hole with the larger bit, but stop short of going all the way through.
Use needle files to enlarge the bottom of the hole to the larger diameter, or
just a tad larger, leaving fingers to form the flutes.
Pound your dowel blanks in from the top side.
Depending on how much use the plate will get you may want to harden it.
Or, you can make one from a standard dowel plate by threading one or more holes
in from the side, and putting in setscrews with sharp points. Back them out
when you don't want flutes. One or two flutes are enough to release the
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