Six hole punch
Modified the original for the six-hole 17mm page for my wife's planner. I added a tab on the bottom to hold with your thumb and two finger holds on the top to help you pull it open. I also added a little gradient ramp to help avoid creasing the paper as you press down on the punch.
Requires a 3mm pin -- I used a bamboo skewer from Hobby Lobby.
Recommend printing at 95% or so infill. To smooth the gradient, use a .1mm resolution.