I have to give credit where credit is due! I totally respect any knitter who takes time to perfect the shape of their knitted items, no matter what fiber they've used.
(What Sue said was interesting, about steam 'killing' the acrylic yarn. Sounds about right.)
I thought the little 10" x 10" blocking board she (the blogger) created using foamcore board and batting was very ingenious! Maybe she doesn't have access to the interlocking (foam) puzzle piece style blocking matts, but has lots of foamcore & batting!
Did she make several so that she could block more than one at a time? Well, I guess one would do.....knit one, then block it while you're knitting the next, eh?!!
They wouldn't take much room, and could sit anywhere in the house!
I've used acrylic for garments in the past, also for afghans. I remember slightly steaming the armhole seams to flatten them, usually on my ironing board. I've pinned out my acrylic afghan squares and steamed them into uniform 6" x 6" squares before seaming. I dunno if it really accomplished a permanent resizing cuz after all the blocks were seamed together, how would one know?
But it made me feel better to at least start out with uniform 6" x 6" blocks aligned as I was in the seaming stage. In the end, my daughters toss the (acrylic) patchwork blankets (knit for my grandkids) in the washer and dryer. They come out fine!
With acrylics.....I've steamed, I've spritzed, I've pinned and prodded, I've used wet terry cloths atop....whatever struck me at the time. I've never been sorry I spent the time trying to nudge my finished knitted items into a nicer appearance.