After further review of manufacturer's photographs of the rear panel, of the M350, I have concluded that there are no stock provisions/penetrations for ANY PCIe slots/brackets in this case ... only ports ... I cannot say what case mods are possible but the case is made out of plastic.
This case looks as if it is made for ATOM based boards ... why don't you just read everything the manufacturer has published and make your own decision?
I've done a build with the M350 and modding the case to add a pcie card would be possible, but not reasonable. I actually modded the case to fit a larger heatsink on my cpu actually and it worked out alright. I used a fan bezel with a filter on top to cover the fan that was jutting out through the top of the case. If you are going to cut the top of the case to fit around the pcie card, you will probably want to think of a way to cover around the card afterword unless your okay with it sitting out like it was a workbench pc. In my opinion, using an APU setup like an A8, or A6 is best for this case. My latest is an M350 paired with a picopsu 160 and an a8. The riser card idea is amazing but i have serious doubts that it has enough airflow for proper cooling. Hope this helps.