Ive done a couple of these now, will post some pics.
RE the insert plate, I have bought
2 of these from eBay for my Triton routers - I know you have to drill them, but I find them really good and strong.
Basic shape dry put together
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Front panel slot cut to allow fixing of movable fence at the front
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Glued up (blocks to keep is square while gluing)
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Cover made to form a dust extraction port
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Pair of panels cut to form the front fences, with threaded inserts added
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Finished main section (nothing to stop you stopping at this point if you dont want the movable fences) (pic also of the router insert I linked too) - note also the hole to add a vacuum for dust extraction
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Complete unit with fences attached - these can be moved to suit the size of the bit your using
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Adjustment knobs on the back that screw into those threaded inserts I added earlier too lock the front fences in place
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