Micro SD Card + USB Jump Drive Holder - Double Sided -
Basically I needed more slots than anyone else had on here and this style worked the best so I mirrored it, flipped and bonded them back to back and it works great!
If its a bit loose feel free to scale it down 5% or so in the x axis, y axis or both until its just the way you like it. I prefer mine full width but shrink the length down to 94% so the drives all fit really snug and dont fall out. Another trick is widen it and still shrink it length wise so there is more flex even though its still snug.
Good luck and enjoy!