On the exploded view, you start at the back with a seal. This can be a simple turned part out of delrin (I use Ikea chopping board plastic).
Next is the bearing block. You size this around you bearings, 7200 bearings are good.
2 Bearing 7200B 10mm Diameter 30mm Angular Contact Ball - eBay (item 360189223748 end time Nov-07-10 18:27:15 PST)
You want that bore to be a sliding fit within about 0.0002". Nice sharp HSS boring bar, with lots of rake, and one just hanging out long enough to reach the bottom of the bore.
This is how you learn precision.
The bearings are shown wrong, as they are both pointing the same way. The need to be inside face to face. A thin shim is used between them to preload them.
The cover of the bearing block should have a boss sticking out on the back the diameter of the bearing, so that it pushes the two bearing outer races hard together.
On set of holes holds the cover onto the bearing block, and the second send mount the block to carrier which mount it to the base casting.