Grinder in a box 2.0!
The new version of the Grinder in a Box makes assembly even easier than before.
First, bolt the main upright to the base.  I used 3/8"-16 x 1" bolts, but there is enough room to go a little longer if needed.

Since there is no countersinking, the bolt heads will raise the base plate.  For this one, I've added other bolts in the corners to make things level.  When mounting to a bench, you can relieve the bench where these bolts are, make a small cutout, or make a stand that is clear in that area.

The holes in the baseplate to mount the base of the motor no longer need tapping.  They are setup for clearance for 1/4"-20 bolts.  The hole size is appropriate to tap 5/16"-18 (as shown above)

When drilling the hole in the idler block, use a vice.  You can't safely drill it by holding on with your hand.  When drilling this hole, I recommend that you drill ream it.  Drill it undersize first, then drill through with your 1/4" bit.  It will leave a cleaner hole.

Here is the finished idler block with cross hole drilled and the hole tapped with 1/2"-13 threads.  

The rest of the idler arm assembly is much simpler than before.  This is how the idler supports are attached to the idler arm.

Using the idler arm as a template, you can either drill all the way through or drill a little bit to mark the hole and then drill through while holding the supports in a vise.

Note the orientation of the nuts (or bolt heads if you put them in from this side).  If the flats are not turned this way, it will impede the rotation of the idler block.

You can also see the shock supports and the bolt for the handle.  The handle attaches the same way as the upright does to the base.

This is the multi platen in it's flat grinding setup.

And rotated for the larger wheel.

And rotated again for the smaller wheel.

And the standard platen setup.