Nice work, Hans!
Having recently done some similar work (see Ataroid: http://forum.arcadecontrols.com/index.php/topic,149221.0.html) I'd recommend using xlr-type panel mounts. E.g for your hdmi:
http://forum.arcadecontrols.com/index.php/topic,149221.0.html
then using this to cut the hole:
http://www.ebay.co.uk/itm/3-Pcs-Large-HSS-Steel-Step-Cone-Drill-Titanium-Bit-Set-Hole-Cutter-4-12-20-32mm-/272422588843?hash=item3f6da6d1ab:g:jXoAAOSwgHZYC1wh
Gives a result like this:
Also - for any other standoffs - i'd recommend using hot glue. Sure - leaves the insides a bit messy, but saves any traces on the outside.