These plastic trays I think came out of a Herman Miller plastic contraption they call "locker" (a high plastic cabinet). One of the trays has a sticker that says "Part number 133141". They are all five made of thick plastic, 19 inches wide with a 5/8 inch lip on each side to slide in and out.
The blue, red, and yellow ones are 14 inches deep with a 3/4 inch pull handle in the front and they are 3 inches high.
The beige ones are also 19 inches wide (plus the 5/8 inch lip on each side) but they are 7/8 inch high and one is 14 inches deep, the other 10 inches.
Along with these trays was the sliding platform seen in the 1st thru 4th pictures. It consists of a metal part with a retainer in the center and 4 studs underneath, and a black wood slider that goes back and forth on the metal base. I am sure it belonged to the same contraption as the trays.
The metal thing is 19 inches by 10 1/4 inches, 1/2 inch deep. 1/16th inch steel. The wood slider is 21 inches by 8 1/2 inches, 1/2 inch thick. The groove in its center is also 1/2 inch wide.
602~697~1877 (OK to call 07:00 AM - midnight. Hablo español.)
(I cancel each ad as the items sell. So, whatever is listed IS still available.)