Everyone has made one of these at some point! The tough part with tape measure yagis is getting the hairpin match connected to the tape. Soldering copper to steel is not easy. Just follow the instructions and get the dimensions right, it'll be close enough. A couple of issues ago QST had a story about a Boy Scout troop making them, so relax and don't worry.
"Stand your ground. Don't fire unless fired upon, but if they mean to have a war, let it begin here." -- Capt. John Parker