If you do a search for "motorcycle lift plans" you can come up with quite a few. Some of the more sofisticated ones they usualy have a charge for copies of the plans. (Then type in "Free motorcycle lift plans"....)
One problem I have noticed is the parts required will sometimes end up costing you more than buying one from Harbor Freight , or even Sears.
I prefer the lifts that pick up the bike by the bottom of the frame as opposed to ones you just ride on like the one pictured above. If you need to change tires you still have to jack up the bike to remove the wheels.
The simple lift type sears and harbor freight sell only really need you to fab up custom supports for your particular bike. This one from JCW is what I am refering to:
For me, there really is nothing at the bottom of a bike I need to mess with, so a nice soft pad for my butt on the garage floor does the trick for me, no lift needed.
(I do have a heavy duty eye hook bolted into an overhead joist in my garage in case I need to hoist up one end of the bike)
One of those little shop stools with the wheels are very handy too, and cost less...