... I still don't know yet about what I'm gonna do with the HuCards that have nothing but the UPCs for the back case.
I think it would be great to at least "emulate" the experience of the early Japanese HuCARDs by including the UPC on the back of the PCMCIA jewel case...
(1) I don't think there is a resource that documents these UPC stickers. If there is, share it!
(2) Your back insert should be solid gray + UPC sticker*.
(3) Real scan when available, simulated sticker otherwise (different companies had different style UPC's, you can alter some info on each UPC to make it unique for each game, like having the title of the game, and the price...purists be damned...the purists can scan the damn sticker if they are upset
)
(4) Now, nobody is forcing you (us) to simply center the UPC sticker...it can be offset, you can zoom in and crop the top and bottom edges of circle sticker, etc. YOU can decide whether you want the "UPC layout" to be UNIFORM (UPC is always the same size and location) or to vary things...
(5) Look below, there is a "common layout" (size of sticker, four horizontal bars, etc. that has some variation in fonts, logos, sizes)
TAITO (Heavy Unit) Masaya/NCS (Double Dungeons) Telenet (Columns)
FACE (Hany on Road) I'MAX (Lost Sunheart) Hudson (Peach Cobbler)
Here is the full-size pic:
http://junk.tg-16.com/images/UPC_on_PCE.jpg