After a bit more thinking, some universal T-bolts for the rip miter fence make more sense than fixture blocks.
The two big slots in the rip fence and the miter fence and the front and rear rails are sized to take 1.00 inches wide x 1/8th and 1-1/8" wide x 1/8th.

So I took some 1/8th flat Aluminum 1.00 inches wide and cut 1-1/8" long to make a 1" x 1-1/8" rectangular plates; I used a short rip fence Block to space the length but not cause a kickback with the...

https://www.sawdustzone.org/forum/di...-rail-profiles

this is a link of a post thread on the subject.

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I am finally going to use my BT3000 extension rails.
My objective is to have some easily attachable rail extensions rather than a full time wide BT3000 using two full rails taking up a lot of space and requiring table support under the right side as many do.
I just want some wider support but not to do full 4x8 sheets of ply... if I need that, I'll break the sheet down on some sawhorses with a circ saw and some guides.

I think I am going to cut my extension...