weight I can't really see being a factor...
2 blocks 10mmx10mmx15mm i.e. way more than these blocks will be. weight the following
mild steel. 23 g
brass 25.5 g
stainless steel 24 g
titanium 13.5 g
lead
34 g
ali. 8g
So any worries about weight are unfounded IMHO.
Remember these are
way over what the item would weigh in at.