Someone on the Lumberjocks forum asked if anyone knew of a Bosch Router Table insert that would accommodate Leigh RTJ400 dovetail jig bushing. I found befloibent's insert and decided it was a good time to learn OpenSCAD to modify it to create a recess so you can mount a guide bushing. The dimension of the recess are parameter driven so you can open with Customizer to change the recess size to match your bushing exactly. You can so just use the parameters to change the size of the opening without a recess to accommodate different bits sizes. You can also download and used OpenSCAD to modify the parameters.

Changes include a minimum and maximum bit diameter and a thickness parameter to adjust the recess depth of the bushing. Make the min and max diameter the same to mimic befloibent's original design.

Note that I have NOT printed this design, but someone on Lumberjocks has and it appears to work as intended. You can see their results here.