I want to order folded greeting cards, but I do not see in any of the options under "buy this photo" to have cards printed.
It appears this is no longer an option in the shopping cart.
You might be interested in this conversation, https://dgrin.com/discussion/264366/cards-option-missing-in-cart. The page https://www.smugmug.com/features/perks shows that cards are available via partnership between SmugMug and Chatbooks, https://chatbooks.com/smugmug/.
I have been ordering photo cards from Zazzle for quite a number of years.
EZPRINTS still has upload your design. I used them many years ago thru Smugmug.
I printed on all sides, outside and inside. 4000x2800 72 ppi
Below is an example of my last uploaded folded landscape card.
Would have to contact them to see if it still works.
front - inside top
back - inside bottom