The Old World: Modular Movement Trays
This set includes the follwoing plastic components:
2x 200mm x 200mm floor sections
32x corner pieces
48x straight pieces
The set also includes a construction manual to aid with assembly.
Guidance for unit bases sizes can be found in Warhammer: The Old World - Ravening Hordes and Warhammer: The Old World - Forces of Fantasy, both available separately.