I used beech veneered block board and used oversize beech strip (tree-wood rather than laminate!) to make the edges, mitred at the corners. I glued the edges on and nailed them (but left the nails protruding) until set. I then removed the nails, filled the nail holes, carefully planed the edges down flush and then sanded the lot down and varnished.
Blockboard bends a lot less than contiboard. It is what you might call expensive though.