"Everything's an antenna", I often say; it would appear just as you. From the DIY plumbing aisle to electrical, to the county recycle yard and any campground I pull in to. Just ask KC8VWM, there's many kindred spirits out here! Cheers, David / N2PQW
100% agree Callum, it's exactly like the 'when you only have a hammer, you look for things to hit' analogy. For an antenna builder, everything has antenna potential either as signal carrier, insulator, or a device to hold it all up. In Finland I built and used a 20m vertical from a Christmas tree stand and Ikea curtain rods... and a 2M halo from a broomstick and building ties. Being above a granite rock, I used an 80m fullwave loop above the (rented) house. In Singapore, it was a 'fishing line' longwire off the third floor balcony after midnight made from a windbreak pole, plastic tubing, and heavy lead weights to stop it landing on a lower-neighbour balcony with RF on the end!
Don't mean to sound rude but he does have the formula right. He is showing the calculation for the lengths of each individual element at 1/4 wavelength long to make up the complete 1/2 wave dipole.
Now this looks like a fun project to try, just my kind of antenna. Having great success with a homebrew longwire and the hobby is much more fun to make something that works well rather than the mundane commercial stick in the sky. Sure go commercial for VHF/UHF but homebrew HF antennas are truly great fun and can be cheap as chips to make.