G
Gazzer
If you dont have the router handy then shape the edges with a block plane and sand to a smooth consistent finnish.
If you need a rebate on the underside to overlap tile;
Set a table saw to the depth of the rebate required
Set the fence guide to 2mm and pass the underside of the timber over the table saw
Set the fence to 4mm and pass over again
Repat this until you achieve the desired overlap on the rebate!
Upload some pics mate when you get done!
This would require the safety guard and kerf blade removing though and we could not condone such an act !