If you don't have a piece of extrusion, you can use a clamp. Remix of Easy Dremel holder for vice by @radicalreel.
I decided to use PETG. I recommend strengthening the entire model and also the walls around the nuts. Unfortunately, supports are also necessary. I chose organic. See the attached 3MF file for detailed print settings.
Consider please using stainless steel bolts and nuts.
If you want to modify the model, I am attaching the STEP file and a link to my OnShape.
You can customize the model by simply changing the parameters.
Please don't forget to leave a rating or a comment. I will be glad for any feedback, so I can correct any mistakes in the design. Thank you very much.
The author remixed this model.
Fixing the Dremel grinder holder with a clamp.