This is a redesign of the Motorcycle throttle lock by toofuu and my previous throttle lock.
It has a hinge and does not need to be inserted from the end of the grip, which makes it compatible with handguards, and generally easier to put on/off even on standard grips.

The hinged body is printed in one piece, use patience and an xacto knife to free up the hinge.

The thumbscrew is mounted on the top of the throttle lock, not in the slot in the body. The body and thumbscrew have detents to limit slip (these might wear out, maybe add a small o-ring).
Use one stainless steel M4 bolt (30-35mm) and a standard nut.

The design can be improved. Any feedback is appreciated.

IMPORTANT SAFETY WARNING: make sure that the head of the bolt fits in the hexagonal recess in the bottom rail of the hinge, where the brake lever slides. It is dangerous to have any protrusion that might interfere with the brake lever operation.

Before you try the throttle lock on the road, familiarize yourself with its operation, adjust the screw tension, make sure nothing interferes with the normal operation of your controls, etc. you don't want to find out something is not working right during a panic brake....

Ride safe!

Version 7 (5 files):

Increased hinge play to make printing easier.
Redesigned the thumbscrew.
Scaled up slighly.

Three versions of the main body are available, with or without small tabs to aid engagement/disengagement of the throttle lock (thanks dmai for the idea).

There are two "small footprint" versions of the design, for printers with smaller beds. They are exactly like the more open version, but the hinge is not as wide open, which might make it slightly harder to open up after printing. Use the larger footprint you can fit in your printer's bed.