Tool for sharpening Planer Blade V2 MAKITA 2012NB

Tool for sharpening Planer Blade MAKITA 2012NB. Simple design. Use sandpaper and neodymium magnets 20mm x10mm x 4mm.
http://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20160331021828&SearchText=Block+Strong+Magnet+20mm+x10mm+x+4mm+
Use square aluminum tube 20х20mm
https://youtu.be/aO1TEemFSq0