Blocking a block

I was in the Dollar Tree the other day and had brilliant idea.  I had been looking at foam craft pieces that you use pins on to block your crochet/knit blocks.  They are pretty pricey for you square.  I found these in the kids education items at Dollar Tree.  This block is approx. 12 inches square perfect for blocking.

I decided to duct tape the backs, so the pieces would not come apart.

Here is two of squares set up on the foam.  The only thing I am missing is grid lines.  I have been trying to figure out the fastest way to do this.  I will add an update if I find a way that makes it still under $5 a block.

I tacked the block down with T pins, then used a spray bottle with water in it lightly made it damp.  The block held it’s shape perfectly.