At the time I solved this by taping the edges of the panels down to the knife edge table, but that was really inconvenient so I came up with a solution for next time. (A knife-edge table is a row of triangles - points up - that you lay a material onto when laser cutting it.)
I designed and 3D printed some clips that would snap down and grip a section of the table, and a little tab that would keep the edge of material held down tight. It's specifically sized to work with 1/8" thick material, but they are low-profile and re-usable.
|Printing on my Raise3D N2.|
|The top of the "V" has a tab to hold material down, the mouth of the "V" snaps over the table support.|