We then came across these collapsible handles made just for attaching to these dollies. The handles actually tuck back under the dolly and snap down into place. Worked out great and thought they made neat awards that were useful. Always looking for something to make for exhibitors instead of trophies all the time.
The only downside is that these aren't real quiet due to the wheels. You'll also need to solder the rear wheels straight to keep them from turning like you need just the front wheels to do.
These would be a great project for 4H'ers. Rabbitry names could be painted or wood-burned on.
I use one to keep a big tub of oatmeal tucked under a table in the rabbitry and just pull out as needed. Much better than dragging the tub in and out from underneath.