I got my giant (9'x12') drop cloth home from the hardware store and spread it out on the floor.....or at least as spread out as I could get it.
Then I marked the middle of the long side (on each long side) so I could make my first cut
Once I had found the middle, I used a plumb line stretched between my two marks so I could make sure my cuts were straight.
And made myself a cut line before removing the plumb line.
Oh, and to make sure the fabric didn't scoot around on me, I put some heavy books and painters tape on the drop cloth. Gotta work with whatcha got right?
With my cut line marked, I broke out my scissors, held my breath, and started snipping. Once that was done, I repeated the process in the other direction to get the proper length. Then I borrowed a friend's sewing machine to hem the two raw edges on each curtain. Easy as pie. Here's the finished (but unpainted) product. Seger photo-bombed.
The curtains actually are painted now. Stay tuned!