This is the tool, you may be able to make one OK.
I think I have an old one if you need a good measurement on the rod thickness.
It's the one on the top left:
The "small" 90 degree bend is the end that engages into the hub, the large 90 degree bend would sorta be considered a 'handle". You do need to hold some pressure towards the hub (towards the fan side i guess you could say) while you turn the bolt to get the tip to drop into a blank hole.
ps I just did a search to come up with this picture of the tool, I know nothing about the supplier on this web page, this is not an endorsement. Looks like a decent enough price though.