In terms of the trash can:
How much will the counter weight weigh? This, we assume, will be anchored to the inside bottom of the trash can so as to NOT flop around during dumping.
What is the dimension from the top rim to the top of the false floor inside the can?
Our tests show that a 20 or 25 lb. weight does the job, so I’m going to probably buy some barbell weights tonight and test mounting methods–most likely a bolt through a centering block, fastened to the bottom. We will get a definitive answer posted as soon as we complete our tests. The false bottom will be a round piece of board that is 14" up from the inside bottom of the trash can. It will be mounted by screws radiating in from the side and an internal shelf block that it rests on. Details should be released this week.
For weighting the bottom of the trash cans, we have decided to use standard domestic automotive steel wheels, approximately 15" in diameter and weighing approximately 22 lbs.; teams wishing to duplicate this for one of their own trash cans can probably get used wheels for $5-10 (and auto supply stores will sometimes just give old ones away since they are often stored out back for scrap pick-up!)
The wheels will have their outer surface face downward so that the lowest CG is achieved.
The wheels will be secured to the bottom of the trash can with some wood shims, bolts and zip ties so that the weight does not shift around when the trash can is getting tipped.
The false bottom of the trash can is made from a round piece of 1/2" plywood that is mounted to the sides with wood screws. The top surface of the false bottom will be 14" above the bottom (lowest level) of the trash can.
This puts the top surface of the false bottom 13.5" below the rim of the can.