Depending on your end desire, funding, etc. Here are some ideas/resources in no particular order:

https://moveunitedsport.org/locations/

Your local prosthetist/orthotist

Monkey feet https://animalhousefitness.com/?gclid=CjwKCAiA0cyfBhBREiwAAtStHLcSmsdX5J9BsSoQCEoXL2Nc3eX7GVt9rHJTDPtJATGzqRX-jwKwARoCRPIQAvD_BwE (Mimic this design for your upper extremity)