Il'd have to agree with Barrie on this one using some scrap card or paper is by far the Cheapest method for glue mixing..
That said i do have a glue mix slab which is made of silicon ( cooking section in B&M ) which cost me a quid a few years ago...
Once the glues dry just give the the board a flex and the remaining glue pops right off for the bin..
Generally i don't use it as i've found that if you done quite grab all the glue during mix up your left with unmixed stuff that just spreads about the mat and is generally a pain in the ass to clean up where as a bit of card once done just fold up and bin..
The Silicon mat is however really handy now for mixing up P38 on!
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