The Raspberry Pi is a creditcard sized computer which you can buy for $25 or $35 (depending which version)

Never designed a case before, so perhaps things can be better...

......

v11 Different splitlevel (more simple) on backside
keep a little margin on back split, so that top and bottom always fit
added openlogo option
added pcbholder option
changed support studs a bit
changed dimensions to 85.0 x 56.20

v12 Different component locations/sizes
keep a little margin on component holes
pcbsize to 57.0 x 86.0 (actual it is 56.17 x 85.0)
made casestuds wider and added 2 minor holes for self tapping screws

v14 Got a RPI.. so production board measurements...

v15 moved the rca and snd a bit to get them more centered
Thanks to lincomatic at Thingiverse
Added option for GPIO side hole in bottom or top
Added showing GPIO pins with component drawing

If it fits or doesn't, please let me know..

The bottomholder_frame.stl is a standlone minimal frame for a RPi.
All the other bottom_xxx and top_xxx.stl files can be combined.
If you want something specific just take the openscad file and alter it, or just ask...