You can use my design if you would like. It's compatible with the stock Tandy plastic.
Pictures live on my web page here:
http://www.nf6x.net/2013/10/cocoeprompak/
Design files (Eagle PCB) are here:
https://github.com/NF6X/CoCoEPROMpak
You can order bare boards here:
https://oshpark.com/shared_projects/aMK1Ekos
--
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/
CoCoEPROMpak v1.0
CoCoEPROMpak v1.0
Text below copied from the original post by Mark J. Blair at the CoCo mailing list. Compatible with both CoCo and Dragon 32/64 machines.