Block before or after?

I’m making a sweater, should I block before I put it together or after?

I believe you block each piece before you put them together to make sure they are the right sizes.

What is it made of?

It’s acrylic but is is curling at the ends. I was thinking it would be easier to seam nlocked. Am I wrong?

Acrylic really doesn’t block, per se. You could flatten out the edges with a little steam to make them easier to sew, but the actual sewing will flatten them out, too. If they’re too difficult to work with, you can either carefully steam them a bit–don’t touch them with the hot iron, or put a damp cloth on them and let it dry. You can pin the pieces down first.