The standard size has an internal diameter of 160 mm

Insert the towel roll, leaving the end of the roll exposed. Rotate the roll clockwise, and the end of the roll should automatically come out of the side slot. Pull a tissue from the bottom up, towards the right edge of the slot.

You can freely increase the height of the stand. I chose a height of 180 mm to fit my bed, and I don't think it's possible to make it shorter, but I don't think there's any harm in making it taller either.

Add three rubber pads or bases to help prevent slipping. There's a place on my workbench to put tissues, so I might use some double-sided tape to fix it and create a semi-permanent "home" for the roll.