There are several old threads on building your own. You might try a search either here or in the photos section.
Here are some of the threads. My husband refers to the first one as "rage in the cage". The second one is Watson's dog grooming arm solution that is quite affordable.
https://www.quiltingboard.com/vbulle...e-t250308.html
https://www.quiltingboard.com/vbulle...a-t303241.html
https://www.quiltingboard.com/vbulle...q-t289959.html
https://www.quiltingboard.com/vbulle...s-t273928.html
https://www.quiltingboard.com/vbulle...e-t256953.html