I made two trailer hitches for my chippers just because they are a pain to move around. I think the steel axle was 5/8” rod from Home Depot. You can see from the photos that it wasn’t too hard to make. I thought on the first one I might take it off while using it, so I added the pins, but that was unnecessary, so the second one is slightly different. I used scrap steel from a local metal recycling place. The width of the tires allow this to now go on all sorts or terrain behind a lawn tractor or ride on mower if you have a hitch. The tires came from HarborFreight. Important was the additional axle tubing between the chipper struts. This provides some additional support. Note the photo with the steel layer out on the floor was from my second trailer, so it lacks the square tubing and pins.