Re: no bottom grate?
For every person I know who leaves the grate in the cage I know another who removes it entirely. There will always be poop in the bottom of the cage AND the grate (not to mention perches) so that concern is kind of a moot point.
However, you mentioned that one of your lovies is shredding so I'd have to agree w/ Lori: it might make more sense to buy a new cage that comes with a grate.
I don't know what kind of wire is truly bird safe and would worry about rough, jagged edges from cutting wire to fit. However, there may be a few folks on here who have contructed aviaries or cages that can give you a better idea.
Best of luck!
Until one has loved an animal, a part of one's soul remains unawakened. ~ Anatole France
Pickle, Golden-winged parakeet (brotogeris). DOH 3/22/08.
Beetle, Peach-faced lovebird (agapornis). 8/6/05 - 8/28/07. Always in my heart.