Specifically made for the Ultimaker but could be used anywhere. The normal hex driver you get has the handle at the same height as the top of the Ultimaker when adjusting the platfrom which makes it hard to get a straight angle on it and get the hot end close as well. This is long and thin which helps all of the above. The grip also slides up and down so that you can avoid putting weight on the platform while you are adjusting it.

You'll need a short 3mm screw and washer and a hex driver tip from a driver set. Optional 8mm X 5mm disk magnet.
Print the shaft with the big part down reasonably firm onto the platform.
If you clean the top of the shaft where the grip slides you need to keep the edges sharp so use a file on the flats and DON'T curl sand paper around it.
Press the tip from a nut driver set into the end of the shaft. Tight fit so you could heat it up first to help.
Print the gripper and use progressive bigger Allen keys to clean it out.
Keep adjusting till the gripper just slides nicely but careful not to go too far.
Stick the washer and screw on the top to keep the gripper in place.
Optionally press in an 8mm X 5mm disk magnet. I have removed mine as it was lifting the platform and it works better without it.
There are 25 notches in the gripper which equate to 0.02mm adjustment each.