This is a force balance designed to be used with a small homemade wind tunnel. The majority of the parts are 3D-printed, and can be made on nearly any desktop printer. The total cost of parts is roughly $20, and little technical skill is required.
Step 1: Print
All 3D models for this project can be found on GrabCAD here: https://grabcad.com/library/3d-printable-force-bal...
Print out 4 female tubes, 2 male tubes, and 2 middle tubes. After printing, some parts, such as the joints, may need to be cleared of support material.
Step 2: Assemble
Assemble the printed parts according to the image above. Use barrel screws at joint points to allow the balance to move smoothly and with as little resistance as possible. Attach extension springs of a known spring constant to the encircled areas, and hang weights from the third endpoint as needed