Advice needed: DIY chair mat

I want to make an inexpensive chair mat similar to the one in the picture to place on high pile carpet. I already have left over materials from other projects:

1/2" OSB sheet

1/2" Plywood sheet

20 ft^2^ vinyl plank (has a thin foam backing)

I plan on gluing the plank to one of the above sheets and then cut the mat to the desired area (56"x48") with a circular skill saw.

Questions: What glue should I use to glue the vinyl plank? Should I use the OSB or the plywood?