I found a nice and simple filament holder for mounting on top of the printer here: https://www.thingiverse.com/thing:5193142 But to work with this ball bearing filament holder, https://www.thingiverse.com/thing:5006390 the notch in the hole needed to be moved. So that's the main part of the remix.
I also added a 4mm hole for a T-nut screw on the bottom. Works fine with this T-nuts where you do not have to take the frame apart to get it in: https://www.thingiverse.com/thing:3050607
I combined all of it with this filament sensor holder to point it upwards: https://www.thingiverse.com/thing:5203968
Depending on where you place the holder on the top frame and the size of your filament roll, it may rescrict the building hight to some extend. Not tested it though, but keep it in mind.