Climax Metals RC-037-4H@90 Black Oxide Plated Mild Steel Rigid Coupling, 3/8" Bore, 3/4" Outside Diameter, 1" Length, 1/4"-20 x 3/16" Set Screw

Makermotor 3/8" D Shaft 12V DC Reversible Electric Gear Motor 50 RPM

Climax Part RC-050 Mild Steel, Black Oxide Plating Rigid Coupling, 1/2 inch bore, 1 inch OD, 1 1/2 inch Length, 1/4-20 x 1/4 Set Screw

Climax Part RC-037 Mild Steel, Black Oxide Plating Rigid Coupling, 3/8 inch bore, 3/4 inch OD, 1 inch Length, 1/4-20 x 3/16 Set Screw

Makermotor 3/8" D Shaft Variable Speed Electric Gear Motor 12VDC Max. 50RPM

Makermotor 3/8" D Shaft 12V DC Reversible Electric Gear Motor 100 RPM

Climax Part RC-031 Mild Steel, Black Oxide Plating Rigid Coupling, 5/16 inch bore, 5/8 inch OD, 1 inch Length, 10-32 x 1/8 Set Screw