Never seen them before, it would be cool for a steem round to be pre loaded with 1 steem, i did think that everyone buying a steem round pays @steemsilverround 1 steem, the round is given 1 steem face value and if anyone wanted to sell in the future @steemsilverround would always pay the 1 steem in exchange for the round, if steem went to $100 it would give the round an extra vaue on top of the silver and collectability.
And another idea, the 1 steem everyone pays is used to power up @steemsilvergold, so if there are 2,500 rounds thats a power up of 2500 steem every year or more depending on the mintage and @steemsilver round upvotes your post at say 5% per coin that you own up to maybe a maximum of 10 so your steem round is also generating a tiny amount of income.
Or you register your COA with a 1 steem payment which is used to power up and every week steemsilverround uploads a post and everyone with a COA just comments their number and gets an upvote after 24 hours, the more COAs that comment the lower the vote, the less comments the bigger the vote and voting is done in random order as the power bar decreases.
Or even better, @steemsilverround posts every day with 10 COA's randomly picked, check if your numbers been picked, comment "woohoo im number ----" and get a 100% upvote on the comment. Everybody would be guaranteed at least 1 upvote a year and we could see which is the luckiest most profitable coin of the year.
I like the idea of a pre-loaded steem round of sorts....although I feel it would have to me made from silver, just my bias. An interesting point you mentioned about the coa which could have the qr code would certainly make things easier. You have some really interesting ideas here!