White styrene plastic T, 0.321" square, 0.106" thickness.

Equivalent cross section and thickness measurements for various scales:

Scale	Dimensions
1/24	7.70 inches square, 2.54 inch thickness
1/32	10.3 inches square, 3.39 inch thickness
1/35	11.2 inches square, 3.71 inch thickness
1/48	15.4 inches square, 5.09 inch thickness
1/72	23.1 inches square, 7.63 inch thickness
HO (1/87)	27.9 inches square, 9.22 inch thickness
1/144	46.2 inches square, 15.3 inch thickness
N (1/160)	51.4 inches square, 17.0 inch thickness