Well on this forum I saw an avatar with a stacked Protostar, how is that possible? Any others I can stack that are not YYFs?
It’s possible to hubstacks any yo-yo. It’s just that some are easier than others. A lot of yo-yos with the “nut and bolt” axle system can be hubstacks easily, such as most of the older Duncan yo-yos.
How about a DM2?
That would require a lot of modding…unless you’re an EXCELLENT modder, I wouldn’t try.
You’d have to tap and drill through the Solid Spin Axle system or replace it completely. I don’t think it’s worth the effort with so many existing hubstacked yoyos to choose from, granted most of them are YYF’s though.