Hal, (7 inch long drill !!! Your dreaming again.) I looked around home depot today and found some plastic mesh with half inch holes.
Re hole size plastic mesh, I only have experience with the 1 inch and for the style of screen sorting I am very happy with it...As the body gets a bit weary after 4 or 5 hours, one could wish that the holes were 6 inches across...Getting the soil through gets tedious
( even on a shaker screen. )...Take a chance maybe, I got the one inch, we'll see how that rates against the smaller...ALSO bear in mind that this is a limited offer of a very sandy site...the rest of your screen work might be in the hill country so the 1/2 inch would be better.
Re the leg Idea, aluminum or electrical conduit is certainly lightweight. Do they still make the pipe flanges that fit most galvanized water pipe ??
That Pat is going to be the King of the screeners with those lightweight, grated frames he found....
different sized mesh for all occasions ..... corner tangs,Manos, Change sorters ( nicks, dimes & qtrs. )
If you can find another bread tray ( so as not to ruin the present one )...you might cut out some of the plastic
cross hatchings in the bottom, still plenty of strength there and gives more room for soil to go through,
part 2...cut off one side of the upright sides. Planning for long hours of screening, undesirable things like twigs and stones can be 'swept ' off the screen without the need for actually picking them up and out.
Look very close at the black frame intop pic of mine,the one side is bolted UNDERNEATH the screen for that 'sweeping' effect...works good for me.
If thats Idahoe's professional opinion I'm never going rafting with him ......Maybe screen mesh bottoms is what they use on the tranquil Snake R in Idaho but it will never float the TX Guadalupe