Been out scavenging for bits for this and checking I've got everything I need. Not sure about the two boards I've found. One's too big and I suspect t'other's too small. No worries though, my local DIY shop will cut up some MDF for me if I need to and he does it really cheaply.
View attachment 70096
View attachment 70097
View attachment 70098
Gern
View attachment 70096
View attachment 70097
View attachment 70098
Gern