XY-table (unfinished)

My contest to design an XY-table
( http://www.bitsfrombytes.com/wiki/index.php?title=User:MarcusWolschon/Challenges and http://www.thingiverse.com/thing:1757)
may have been too complex a task, so I designed
the basic frame myself so you have a starting-point.

Required work:
* add a work-surface
* add a handle
* add an additional piece to hold the captive nut in the middle and screw it to the inner side of the frame above to make it move
* add holes to mount it to a table
* take away some material on the bearing-hole to remove the overhang
* add a smaller hole behind the bearings, so the (moving) inner part of the bearings do not touch the frame (easier movement) but only the outher part (static) does.

The parametric original files for this assembly are included.
They should stay within the limits of the free Xpress-version
of Alibre Design but you can use the 30day test-version of it as well (as I did).