This design is based on the magnetic carriage for Kossel posted on YouMagine by Haydn Huntley at: https://www.youmagine.com/designs/kossel-plus-magnetic-effectormodified for 10mm ball bearings with m4 threads available from hksupport's ebay store: 16-x-10-M4-Threaded-Steel-Ball-Rod-Ends-for-Kossel-3D-Printer-Magnetic-Jointsfrom http://stores.ebay.com/HKSupport?_trksid=p2047675.l2563