Since it would be quite heavy, maybe you could attach casters to the bottom of the barrel.
I have only seen people put casters on them to move them around.
https://www.pinterest.com/pin/427349452142623819/ They look really pretty!
Hi Wendy. A few years back I bought a "dolly" and put my whiskey barrel on top of it. Worked well and was fairly inexpensive. Be sure to put the barrel on the dolly before you add dirt. Good luck Wendy.
I have added big caster wheels to one a few years back.
Hi! A flat base for it to sit on and heavy duty wheels would work well. Or you purchase a wood dolly for it to sit on. I use dollies to wheel water bottles, heavy plants, furniture and even an air conditioner to save my back. Just watch the weight limits for wheels or a dolly so it is safe. Wheels that lock will also help keep it where you want it.
A few years back I had a very heavy plant in a container. To move it in the house to overwinter, I had it on a wood heavy duty plant stand on wheels. The plant stand was about 4-5" tall.