1. Giddings and Lewis Variax. http://www.giddings.com/.
2. Ingersoll. http://www.mel.nist.gov/gallery/hex/hexph.htm.
3. Toyoda. http://www.toyoda-ouki.co.jp/_pub_html/.
4. Geodetic. http://www.hexapod.co.uk/g500.htm.
5. Pathfinders. http://www.execpc.com/pathfinders/construct2.html.