You are joking, right? So said the AF model while bending over in his Hollister jeans taking it in the asshole after doing reverse swiss ball oblique presses......... Get real.
regular 2x4 oak or other strong wood fits right into the slots.....get enough 2x4's to make them as high as you need and screw in some reinforcements on the bottom and sides....i used the extra 2x4's i had left and screwed one longways on the bottom of the sawhorse and one on each side (the "V" part of it).
wish i was at the house, i'd take a picture......if you don't make them too long, they will support more weight than you think.....i've read some folks popped 500# on a wooden sawhorse and it held up. 2x4's on the long-edge are pretty damn strong.