These picnic tables are each made from a single sheet of plywood, take about 30 minutes to mark out, and about 1 hour to cut out. The sanding and painting is down to the individual, so I'll not quote any times for these two processes, but I have finished mine with a combination of wood preserver on the undersides and gloss paint on the topsides .
A short video of me assembling and disassembling one of my picnic tables: http://www.youtube.com/watch?v=xATfmOkLh7Q&list=UU1iX9q83W978_o37wLxqkvw&index=2&feature=plcp
You will need a copy of the plans, which you can download and save from here:
To mark out the plywood, you'll need: a rule or tape measure, a pencil, a square, and a straight edge of about 4 feet long, or slightly longer; a planed 4 X 1 piece of timber just over 4 feet long, or a length of steel are ideal.
I have used a cordless jigsaw for the rounded cuts, and cordless circular saw for the long straight cuts, but a jigsaw will be more than adequate for all the cutting requirements.
Pay close attention to the plans, as they follow both a Centre Line set of dimensions, and Accumulated dimensions from the bottom edge of the sheet of plywood. The only really tricky part of the plans and the dimensioning is ensuring that you follow the accumulated dimensions correctly and mark out accurately.
Note: I have used 18 mm thick shuttering plywood rather than the recommended 1" thick plywood: so if you follow my lead here, you'll need to reduce the joint let ins from 1" to 18 mm.
You will obtain a good quality of cut if you use a jigsaw blade that cuts on both the up stroke and the down stroke.