I originally had a 3.5" built in card reader on my previous PC, but when I got the current one, there was no space for it

Least I thought there wasn't - it's a Dell Optiplex and they have funny shaped fronts and the only spare 3.5" bay had a curved front with no cut out. So I sold the card reader and used the portable one I already had (it's a card reader plus a 16mb built in flash drive)
Only a couple months ago did I realise (while I had the case open) that the curved front on the spare 3.5" bay was only a blanking plate and you can remove it to show a cut out for a 3.5" drive, such as a floppy or card reader
So I either want to buy a new interal card reader, or prefferably, a desktop free standing one, but I can't find one that has a built in "stand" to sit on the desktop