I see them on the news all the time. The letters are about 2 feet high and each letter is printed on a single sheet of something - paper, cardboard. Wherever they get them, it must be interesting when someone orders some vile message.
Could be homemade, could be ordered from any of a number of print shops. Even from a print shop, it’s likely that the only human who interacts with the letters is the customer.
It wouldn’t be hard to make them at home in one’s garage. Just takes some labor. And even if printed at the shop, the letters might be printed just one at a time, which might not catch attention from the shop. Imagine if someone printed “YOU F____ING N_____R” but the letters were printed in the sequence of R, I, G, N, R, G, E, K, F, C, N, G, U, I, U, Y, O,” one at a time. No store employee or boss is going to notice or care.
In this website, you get some clear pictures of the letter signs. You can see the fonts are not precise across the different signs. Note the different S and Gs, the different size serifs. They could be made with poster paints by the people holding them.
You might use a video projector to show the image of a large letter from a computer screen onto the surface, and then fill in with paint.
They can be made, of course.
But there are vendors of letters. For schools and businesses. You can get them.in any size. I imagine they do a snappy business.
Hobby Lobby or Michaels.
Especially not if the customer sent the job to the printer from a self-serve kiosk, or over the Internet. The print shop employee might not do anything more than pick up the stack, hand them to the customer, and tell them the price that the computer readout tells them. If even that.
There’s only one “G” in “YOU F____ING N_____R” and you forgot to print the underscores.
This right here, Make them yourself, or buy them. Even if you make your letters small, there are copiers that can blow your letters up to whatever size the copier can handle. Attach your giant letter to a stiff board, and there you go.
Years ago, in the 50’s, Popular Mechanix magazine printed plans for large things to be cut out of plywood. The plans were approx 2” x 2” and meant to be mounted in a film slide mount and projected onto the wood. You’d then trace and cut.
Computers have made things much easier.
You could also draw the template on clear plastic and use an overhead projector to throw it onto the substrate.
My wife and her friends make the letters, cutting them out of fabric, tarp material, oaktag or whatever. I recently got asked to sort them all.
We’ve learned to use mesh (eg a volleyball net) to mount them to, to mitigate the wind effect.
There’s a mural on my daughter’s bedroom wall that her uncle did for her. That’s exactly how he did it.
I belong to a group that has made and placed such signs, and we bought large sheets of black foam core, then made the letter forms with white two-inch tape.
As I recall, Microsoft Excel supports graphics large enough to be printed over multiple pages both horizontally and vertically. Allowing for some edge matching due to home printers having margin limits, you could do it that way.
MS Word will let you print up to font size 1638, which makes each letter > a sheet of 8½x11" copier paper; about ⅔ the size of 11x17’ sheet of paper. Print that, run it thru a copier on enlarge, then cut out (the two pieces) & trace onto what ever you want your sign to be made of. This can probably be done self-service at your local library.
Small letters (a, c, e, etc.) on a standard white on green highway exit/directional sign are approx the size of a sheet of copier paper; any letter that is capitalized or has an ascender/descender (‘tail’ - b, d, g, etc.) are obviously larger.
So really the bottleneck is home printers maximum paper size.
And ink. Probably only get a couple of letters per refill.
I’d make stencils from cardboard*, and use spray paint.
*Plenty of examples online, eg here.
A feature that most people never use & others only rarely used while both costing more in materials & requiring a larger footprint (just for an 11x17" paper tray) is probably not worthwhile. I’ve done something like that, only a couple of times, I just went somewhere with a larger, more commercial printer than I owned. The cost of the one (or two) time ‘rental’ at the library or Kinko’s (as it was known back then) was much less than it would have cost me to purchase a more capable printer.