I've seen them too, and in fact, made 3 of 'em. My advice, look for old wood frame single glass windows - I got lucky and my neighbor was having the garage windows replaced, and throwing the old away. I SUGGESt you carry a tape measure with you, and at garage sales, heck, even in the alley on garbage days, scope out the old windows, but CHECK the deminisions of each glass pane... I found it easier nad less $$ to find/use windows where the pane is not over 12 inches in either height or width, because, you can pick up a package of about 6, plain 12"x12" mirror tiles for about 6 bucks at Home Depot, etc. This way, you simply remove the old glass, measure for the mirror, and use a regular old glass cutter to snap the mirror to size. I install those little glass points, and then caulk a bit. No need to be extra careful as the wood side is the one that shows. I put two of them together as if they were installed that way, looks great on the porch. Also did another one and attached a pine shelf to te bottom, hung it and it looks like the window sill. Fun, eash and interesting project. Try it!