If you need extra support for your arm while painting, try a mahl stick. It's a simple tool artists you can either buy or make yourself.
Artist Mahl Stick – Whiskey Painters
Miniature Painting -- Art Glossary Definition
Creative Mark Professional Mahl Stick for Painting, Drawing & Sketching Classic Traditional Artists and Sign Painters Tool- Expa
Artist Mahl Stick – Whiskey Painters
What is a Painter's Mahl Stick?
Mahl stick hi-res stock photography and images - Alamy
Quality Material Selection: the holder of the mahl stick is made of aluminum alloy, heavy duty and sturdy, reliable and safe, stable in structure and
Mahl Stick for Steadying Painter Hand 32.7 Inch Artists Drawing Tool Artist's and Painter's Hand Rest Tool with Artificial Leather for Painting Art
What is a Mahl stick (Make a Easy Cheap one) painting for beginners
How to make and use a mahlstick for painting
Painting
Studio Equipment: Mahl Sticks
Mahl Stick Ball Mahl New Adjustable Stabilizing Tool for Supporting Artist Mobility 33 & 48inch