I designed a Powerpoint presentation and would like to convert the design into a PPT template. is it possible? and if so, how? i don't mean to "save as" .potx but to actually auto create the master slides according to the design.
If you've based your PPTX on a blank master and put all the design elements onto the slides themselves, you'll need to transfer them to the slide master + layouts of your deck (better, a COPY of your deck), then remove them from the slides themselves.
There's a lot more to creating a USEFUL template than meets the eye, though. If you want to learn how to do a good job of it, look for a book called "Building PowerPoint Templates Step by Step with the Experts" by Echo Swinford and Julie Terberg. It's available on Amazon and other places.
Disclaimer: they're friends and colleagues of mine. I have no vested interest in the book and in fact have bought the hard copy AND the Kindle edition because it's that useful.