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Make sure you have customized your size correctly in the software program. Click on "slide size" or "page size" and customize to the needed width and height. For example, 36 in. width and 28 in. height.
Save your document to a .pdf and send to the printer.
Notify the print services attendant that your project is a large-print item and ask for assistance establishing the appropriate settings.
For the McKeldin Library printers, use FoxIt Reader rather than Adobe to print your pdf for a clearer print job.