I have a printer that can normally print up to A4 (8.27 x 11.69 inches) or US letter size (8.5 x 11 inches).
I'm thinking of keeping the width the same (8.5 inches) but increasing the height, based on an aspect ratio of my choice such as 21:9, 17:9 or 16:9 . That way, I can get larger prints without having to buy a new printer, and I would anyway like a wider aspect ratio than A4. In other words, A4 is too squarish for my taste.
The printer driver lets me define a custom paper size:
But I haven't seen any documentation saying that the printer can print larger than US letter or A4. Does anyone know if it can? Do printers normally let you increase the paper height beyond the documented number while keeping the width the same?
I checked the PDF manual, and it tells me to refer to the software for the supported paper sizes, and the software seems happy with letting me print larger sizes. On the other hand, the aforelinked spec page doesn't say so.
Since I can't get paper in these custom sizes, I'm thinking of buying A3-sized glossy 240 GSM paper and cutting it down to this size using scissors. Do the edges of the paper need to be perfectly straight for it to not get stuck in the printer?
I'm assuming that if the printer can print borderless on 8.5-inch wide paper, it can do so no matter the height.
Is there anything else I need to keep in mind before I try this out?
 Or, accurately, 9:21, 9:17 and 9:16.