Here are my helpers... they actually did a good job using the screw gun as well as hammering nails. I started the screws/nails most of the time but they were really getting the hang of it after the third frame went up.
I've probably explained this before but the trellis is for the melon vines to grow up. When the vines produce fruit and the melons get to about one pound then we are supposed to make little netting 'hammocks' big enough for the full grown 10 pound watermelons and tie them onto the wire mesh. This way the melons don't ripen on the ground and it avoids fungus growth as well as lopsided friut.
The individual frames were actually quite sturdy but I put the cross beams on as an after thought just in case.
The metal mesh is heavy gauge so I have no fear it will hold several 8-10 pound melons as long as they are somewhat evenly distributed... that of course presumes my plants will produce well.
The tomatoes are finally starting to develop thicker stalks and I am thinking they should do ok as long as the growing season is long enough... as I said before, I got them in the ground a bit later than I wanted.