A while back I purchased a 1/4" thick rubber mat, 1200 x 600mm, to use as an underlay when glueing up parts (it would fit the bench top here perfectly if the fence was not in the way).
No more concerns about getting glue on work surfaces ..
This panel, 300 x 600mm, became a fold-away extension for the bench. Folded down ...
Folded up ...
Folded down ...
The extension is attached with piano hinges, and secured in the up position with gate legs. I added a bolt for any fine tuning, if needed.
It is all perfectly coplanar ....
Regards from Perth
Derek