Making Matters: Photogrammetry to produce casts

Many violin makers rely on their collection of classic Italian violin casts as a reference when making new instruments. Casts are a great source of information and inspiration for the shape of arching, which plays an important role in the sound of an instrument.

Casts are commonly made of plaster, or plastic polyurethane from silicone negative moulds. Alternatively, plastic 3D prints can be made from CT scans or laser scans. A newer method that I’ve used in my workshop to record the arching of fine instruments is photogrammetry. This method involves taking many photos of an instrument with a digital camera, then downloading the images into Metashape, software by Agisoft, which analyses and stitches them together to form a three-dimensional digital model of the instrument. Once sized correctly, it can be 3D-printed or machined using CNC (computer numerical control) into a full-size model of the arching…