Agree with Richard. If you have to normally buy lengths and saw them down for whatever you're doing to that length, then you hit a good deal for you...
HDPE - perfect! Menards has carried black for a couple years. Searched and discovered they now also had white 4x8 x.25" thick in stock for about $90....
Is there such a thing as a design program that allows you to draw 2D front, side, and top views of an object that will then put them together to make...