Holder for cheap-o deburring tool from Amazon
Sized for a slight interference fit, may need to thicken a wall depending on actual tool size.
Mine is 12.52mm across the flats.
https://www.amazon.com/gp/product/B09376DFYP/ref=ppx_yo_dt_b_search_asin_title?ie=
The author remixed this model.
Custom holder for deburring tool