I use Cabinet Grade Maple Plywood for the sides, back, and bottom of the Trundle, and Select Pine for the Trundle Front. The Trundle is on casters/wheels which are non marking, and also great on low knit type carpeting. The Twin-XL Trundle accepts a Twin-XL size Mattress not exceeding 7.5 inches in thickness, and has a weight limit of 275LBS.
* IF BUYING A TRUNDLE WITHOUT THE PURCHASE OF A BED, THE TRUNDLE MUST BE PICKED UP IN HIGH POINT,  NORTH CAROLINA.
I no longer use the wood drawer pulls. I instead use black metal cupped style pulls (as pictured here) to stay in compliance with codes. 
*This price is for the Twin-XL Trundle only. The Bed is sold separately.