Go to the DESIGN tab. Find the CUSTOMIZE group at the far right end and click SLIDE SIZE
Click on CUSTOM SLIDE SIZE
Choose the size you want in the popup box, select from preselected sizes or use the WIDTH and HEIGHT boxes to choose a custom size.
PowerPoint will ask you to either maximize your content or scale it down to ensure best fit. Pick one of the options.
Your PowerPoint is now sized and ready to print!
If you are using a custom font in your poster you will need to convert your text to shapes before sending us the file. This ensures that the fonts open properly when you send them to us.
It is a little bit more difficult to do this in PowerPoint, but definitely doable.