Let me start by saying that, I used the propagation box from Freeplants.com with great success. The box filled with wet coarse sand and an aquarium weighed 60 to 70 lb, which was a little to heavy for me to be moving around (I'm almost 70 yrs old). I made 6 boxed and they are still in good use by my Daughter and Son in law. I liked the idea of little_dani's Easy Propagation Chamber but thought it would be a little to small for my use.
I found 2 food storage containers at Walmart one a 20 quart and one a 12 quart with the same dimensions around the perimeter. I drilled six 5/8 in holes for drainage in the 12 quart container, and lade a piece of hardware cloth on the bottom to keep the potting soil from washing out. (photo 1) There is a little gap at both ends of the containers, allowing for ventilation, no need for further holes. ( photo 2) . For the potting soil I use 50/50 peat moss and vermiculite. What I like about the near transparent container for the bottom is you can see root development and water needs. Photo 3 shows root development and beads of condensation which indicates adequate air space and water. Each container will hold 120 to130 cuttings and all seem to be doing well and pass the tug test. (photo 4) When I stick the cuttings, I will leave them outside in the shade for 1 week and then move them to the greenhouse. Six chambers fit on an 8 ft shelf very nicely. (photo 5). I also use a 24 in bungie cord to keep the two containers aligned.