Interchangeable bowling apparatus

An interchangeable finger insert system for a bowling ball, the system comprising:

• at least one outer cylindrical body configured to be pressed into a blind hole in a bowling ball, the outer cylindrical body having a smooth outer wall and a hollow inner bore with an inner wall having an engagement feature;
• at least one inner thumb insert comprising:
• an inner thumb slug formed of a first material and having an access opening therethrough, wherein the access opening is configured to be drilled to form a sized-thumb hole;
• a sleeve formed of a second material and secured to the inner thumb slug, wherein the thumb slug is accessible at an open top end of the sleeve and a base encloses a bottom end of the inner thumb slug,
• wherein a corresponding engagement feature is formed on an exterior surface of the sleeve to allow the inner thumb insert to be rotationally inserted into the outer cylindrical body,
• wherein a fastener-head feature is defined in the base of the sleeve and is accessible through the access opening to allow the inner thumb insert to be mated to the outer cylindrical body with a tool adapted to engage the fastener-head feature.