I have a #leifheit Regulus vacuum and though it would be cool to have a #drill-dust collector that would fit it.
That vacuums adapter system MUST be designed to infuriate 3rd party designers.
The shape is roughly oval shaped but NOT. Everything has different radii.
Measuring it all and finding a solution using bézier curves turned out to be a multi hour challenge!
But now a re-mixable shape exists 
enjoy
https://www.printables.com/model/1212897-leifheit-regulus-vacuum-to-drill-dust-collector-ad
