I made this for the JIS bits in the VESSEL TX76U, they're 18mm as opposed to the 20mm of LTT bits and they kept falling out of the holders.
to use it just put a thin layer of Blu Tack or other pressure-sensitive adhesive on the bottom of the spacer and put it below the bits, see pictures.
note: i only tested and printed the 3 bits version the others you'll have to test for yourself
here is the model's source
The author marked this model as their own original creation.