Spoil board MDF alternative?

[WillAdams (William Adams (Carbide 3D))]

The foamed PVC sold as plastic lumber seems a good option — I used it on my SO3:

A different sort of filler strip

Decided I wanted a slightly more efficient usage and mounting of filler strips, so this is what I came up with: the existing strips were cut off a bit shy of the working area at a 45 degree angle, and additional holes added to secure them just short of where the angle meets the baseplate underneath the wasteboard strips were then cut at a 45 degree angle so as to fit snugly underneath at the back, and at the front to fit, and a hole with a countersink to accommodate a nylon bolt was cut in the…