Use a form (or put a black or white plain color paper behind it) with regular cards and scan with the lid open.
For the acetate card, you scanner whiteboard may be an issue, put some other clear white piece of paper over it, and again try to scan with the lid open.
There are just ideas for myself that I haven't gotten to try out yet. So far I haven't run across any card types that can't be scanned besides lenticular cards.
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