Top-down: Thermoplastics handle from an old door, cut & drilled to accept the side bolts into the brass standoffs. Long bolts hold the drilled and turned standoffs (former electric plug pins) and the 3 pieces of hot rolled to the base plate. The two 30 x 10 (205 & 170mm long) pieces are slot milled for less springiness with full parallellism. Distance flat a mere 30 x 5 x 105. Base plate (100 x 54 x 32 mm) and arm from a cut, milled & faced old stage weight of lo-grade and porous grey cast iron. Arm pivots on two side mounted hollow point grub screws pinching (by 4 mm ball bearings) a 2 mm thru-hole in the arm, Feet outta 12 mm ball bearings (HRC 60-64) pressed into base, ground and honed flat. Footprint/dia 11 and c-c; 190 x 38 mm. (The Rahn original boasts an overall length of 10" - which is absolutely unwieldy on my small plate). M5 & M6 Allen bolts 12.9 grade throughout. - The tool's dimensions isn't crucial as long as the feet are parallell. Barely visible is the arm's "Travel Lock" made from yet another turned and tapped electrical 8 mm plug pin. Hallmarks of DIYSwede's Workshop: simple, rough, operational and free, as well as positively accurate and absolutely repeatable.