I got fed up with just a threaded rod and washers and everything going in crooked, so I designed and 3D printed adapters to use with ZS44/56 and DUB bottom bracket press. The last token works like a centering tool, so everything is going in straight. I added axial bearings, but I don’t think they are neccesary. All that and I am on 40% of price of the cheapest press, that does not even have speific tokens, just a flat. 3D files here: https://www.printables.com/model/498142-headset-and-bottom-bracket-press
This is a great idea since those presses can be pricey. I’d rather the plastic bend than my headset so this looks safer to use.
I don’t think the plastic would bend much, but with the linear bearings added you can feel really well how it is going in. And I saved a bunch of money, that is true.