Extruded light grey ABS square tubing.
Acrylonitrile Butadiene Styrene (ABS) is a good all round plastic that offers good impact strength and can be used for architectural, engineering, scale model, model railway other scratch building projects.
ABS can be glued to itself with a methane based cement such as Plastic Weld.
When gluing to wood use a good quality PVA, a medium viscosity superglue is good for most other purposes.
Cut with a fine cut razor saw.
PLEASE NOTE: measurements given are outer measurements.