White styrene plastic T, 0.198" square, 0.065" thickness.

Equivalent cross section and thickness measurements for various scales:

Scale	Dimensions
1/24	4.75 inches square, 1.56 inch thickness
1/32	6.34 inches square, 2.08 inch thickness
1/35	6.93 inches square, 2.28 inch thickness
1/48	9.50 inches square, 3.12 inch thickness
1/72	14.3 inches square, 4.68 inch thickness
HO (1/87)	17.2 inches square, 5.66 inch thickness
1/144	28.5 inches square, 9.36 inch thickness
N (1/160)	31.7 inches square, 10.4 inch thickness