There are different ways, either you print a prop that fits without shaft yourself, get a printed one from propellerking or you build an adapter for a commercially available prop. You need to fix the prop to the bell, normal 63xxx motors have the shaft on the wrong side for our application, it does not stick out at the bell end.
Here you find some ways people built a shaft adapter: Props for 6384/74 motors no shaft - #5 by Riversurfer
Here you find my solution: Daniels (un)geared inflatable (slowly built) - #55 by sat_be
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