General Rule: Don’t reinvent the wheel. Use your time wisely. If something already exists that will serve your purpose, then it is probably a good idea to purchase that item to incorporate into your design. Determine what you need, find several items that might work, look at the specifications for the items, and make a choice on which one will work best.
Gearmotor for Translation motion
Gearmotor – Right Angle Shaft mounting bracket with holes
Gearmotor with Rotating Arm
Micro Gearmotor you may need to fabricate or purchase a bracket
Homemade Lead Screw
Servo Valve
Standard Servo with Linkage