Not sure how you would fab this up but you might keep an eye out, I picked this up about a decade ago as an NOS piece from ebay. The pop up every few years.
68 and 69 and 70 (only with rally dash) used this same part.
The 68 and 9 will say "solid state by plymouth" on the radio face.
70 with rally dash only (dart or duster) will say "solid state by Chrysler"
The 68/9 Barracuda and 70 duster or dart (with 70 rally dash only) mounted with the same bracket and used the same basic radio.