As I got an extra pair of joy-con and their straps laying around in my house, I decided to take my caliper and design this stand.
It can handle a pair of joy-con and their straps without taking too much space. Rails for joy-con and straps have a nice fit, so you don't need to force on your joy-con nor your straps to get it in place.
Feel free to modify or tweak it as you wish, as I left the STEP file here too!
Printing take about 1h30 for me, with 0.2 resolution and 30% infill. I don't think the infill or the resolution are very important, make as you want!