Looking good two things I would reccommend;

1: I'm sure you know this already but you can score aluminium up to about 3mm and it makes the whole 'using metal fatigue to get the size you want' process a lot neater (I've been there!)

2: For the grabber you're probably going to want a little bit of flex to stop the servo stripping itself - in ants a few people have used clampers made of stiff but springy wire for the purpose. If you can get a decent mechanical hold on the other robot they shouldn't be able to get out flex or no flex!