I've got an 8X10 from the folks in MattKings link. Still haven't used it BUT there's no reason it shouldn't
work right. If weight is important get a weight from them, the 8X10 is just under four pounds.
It isn't a beautiful piece of work by any means(seems to be 1X2" and 1X4" pine) and all the joints are
butt joints assembled with nails. I got this used(lightly) and one of the joints had
separated so I put reinforcing metal brackets in each corner. The smaller cameras may be
less crude but very workable.
I’ve checked on their website and the 5x7 is 1.4kgs without the holder. Plus the tripod, plus the sheet boxes, plus the exposure meter, the changing bag and a bottle water and some light food.
Way too heavy.
The camera needs to be under 500grams.
I take photos out in the nature I just can’t carry that load when walking 7+ miles, but I’m also aware that lightweight thin wood like plywood can have leaks through the pores like mine has.
I’ll search for it a bit more, the greek stuff seems okay but I need more possibility.