A laser level casts a straight line, leaving your hands free to do work. An easy way to align mirror clips is in the shape of a peace sign. Put away your tape measure and let the level be your guide.

Hilary Reid is an inveterate eBay shopper and museumgoer who loves tracing the origin of trends — from flight-attendant jumpsuits to the resurgence of marzipan — and collecting NYC merch. If you’ve ...