Hi,
i recently modeling a box (printable), to contain a RPI3 B+, power supply, USB capture stick, plugs (USB, Leds, RPI HDMI out, USB stick HDMI in, network, etc.) : https://www.thingiverse.com/thing:4840960
It can be improved (a lot), so you'll find the link to Tinkercad on the thingiverse page if you want to adapt this to your needs. So i hope to see a lot of remixes !
Have a nice day !