Dumbbell Clamps 25mm
You may need to scale the part up depending on the type of rubber or silicone you use. 1/8" silicone made hard to close, reprinted at 1.03%.
Recommend printing solid.
Used 16 x 1-1/4 brass nails for hinges.
Can scale up to work with larger diameter bars. 120% for 30mm, 205% for 2Inch.