This is my take on a multi-role antenna. It's a dipole that can double as a vertical. It uses m10 threaded 17' whips for either configuration. Can be configured from 6m-20m and if your clever hang a couple 16ft wires off the ends of the whips to get to 40m.

I recommend printing at 50-60% infill for strength

I use these couplers: https://amzn.to/486gjDw
These screws to hold the couplers: https://amzn.to/3JNKBTD
And this SO239 mount: https://amzn.to/4piNZ7N