I wanted a pencil cup that I designed, so I drew some splines, laid down some lofts, and replicated them like mad. You should scale the cup depending on the size you want and your max print volume. Most typical pens are around 120-130mm long, so it should be close to what you need already.
All the overhangs are under 45 degrees, so you probably won't need supports. If you need supports at 45, then I recommend setting your support angle to something lower (35 to 40) otherwise your supports will be tiny little sticks just holding up the very tips of the cup.