I don't like the fiddly nature of the flow control kit for my Profitec Pro 600 offered by the official kit. This is an adapter that changes it in two ways:

• A longer lever to be more like the “paddle” offered on other machines
• A 3:1 gear ratio meaning ½ rotation of the “paddle” will get you 1.5 rotations of the flow control knob

Due to the heat put off by e61 grouphead's PLA is not suitable for this print. Especially for the platform and gear touching the metal of the machine.. PLA will become loose and it will not function at all. I used ABS but I think PETG may be suitable too.

The project also requires a 5mm metal rod to handle the 3:1 torque transfer between the gears. I tried plastic but it shredded itself. The ends of the metal rod need to be filed down flat to connect the endcap and other pieces.

Notes

Since trying it out in my espresso workflow I don't like it for a few reasons sadly.  The Flow Control knob I have (and maybe yours too) is too stiff and doesn't move smoothly.  That coupled with the 3:1 ratio make it very unsatisfying to adjust this way.  Also the process of filing flat ends on the steel rod is horrible.  I'm leaving this up though along with these notes as well as a link to the exportable OnShape project in case anyone wants to try making remixes:
https://cad.onshape.com/documents/dd46fc6408fbf69ad30e092d/w/5d3f940826bb878b0d277d12/e/69b28f9529a7019872375b0e