Summary

First of all, thanks so much Mr. Heinz, your design is amazing.

This is a full M8 version of the original BoltHobber. In other words, it is designed for:

Instructions

Print it dense like:

Metal parts:

Step-by-step:

Insert the M8 nut on its housing located on "slide" part;
Screw the adjustment screw just to put it in place;
Insert the only the internal 608 bearing on slide part;
The other 608 pair will be attached on tap screw body.
Insert both 608 bearing on base;

Place the M5 washer (or metal piece) on top of the Base bridge.
It is necessary to distribute the force along the plastic
Assembly both printed parts as the picture shows;
Insert the Hobbed bolt candidate through the 608 bearings.
Make some measures on your extruder to make sure that the channel will be done on the right distance from the screw head.
You can add some washers to adjust the distance.
Screw two M8 nuts to fix it in place;
Now add the remaining 608 bearing on the tap screw body and insert it on slide part;
Adjust the distance/pressure by the top M8 screw;
Turn the tap screw and follow the results on the small window;
You can repeat the steps 6 and 7 until you reach the desired depth.
Release the adjustment screw and pull the tap screw;
Release the two Hobbed bolt nuts and pull it from slide part;
The 608 bearing will not slide trough the screw due the burrs, so grind it off and the bearing will pass.

Now, be happy with your powerful-not-expensive Hobbed bolt :-)