**Warning use at your own risk, I disclaim all express and implied warranties** I am assuming that you have a wire cage cube. Under the cube, take the same wire and make a carrier not more than a 3" opening. This way the tray will not be cantilevered and has a nice place to sit. I would recommend using c clips to attach it. So basically, if I failed to explain this correctly, you are going to have something like this |_______|
You are going to bend the | at 3" and the ____ length will be the width of the tray. Once you have manufactured this aspect, I would recommend having bass equipment make you some stainless steel trays. I believe they are 2.5" tall, this will work well with the 3" gap. Note, you can adjust the gap. If you have a concrete step you can bend it on that pretty easy by taking a 2x4 and sitting on it or stand on it while bending. Make sure to mark off to make sure the bend will be straight. You can also use a metal brake if you have access to one, this will make for a nice straight bend. Also, once the tray is done, I would recommend putting down a paper bag (open it up if you have to) and place the shavings down, it will make it much easier to clean.
Furthermore, if you would rather not order the pull out trays if you have access to purchase stainless and you have a spot welder and a metal brake you will be fine. 19 gage stainless should be sufficient. I believe that bass charges 29.99 to have it made.
Hopefully this has helped.