Hi ginggs,
I haven't actually gotten a chance to print it yet. The 3d printer has been busy with other people's stuff!
I'm pretty sure you'll need to use #6-32 to M3 Metal Standoffs (See
http://amzn.to/2anqXwz). These are the standard height used in ATX PCs.
If you do print these, can you please send some photos the shield and of the Opsis in the case with the shield?
Thanks!
Tim 'mithro' Ansell