I picked up a 1.2 oz block of this polishing compound from Taylor Toolworks  and I thought it would be nice to have an applicator to hold on to, and a cover to keep fuzz off of it.

The dimensions of what I received are 18.8-mm in width,  61.8-mm length and 20-mm high. The shape is trapezoidal in cross section, with rounded ends and top.

It does not look quite like it does on the website, so I am not sure how consistent these are. This may or may not work for you.

Part shown is Sunlu black ASA 0.35-mm lay height, 30% fill. Overhangs are 45° so no support is required. Brim is not necessary. Material, layer height and fill percentage are flexible.

It is designed to be a light press fit for the compound to hold in to the base. The base is extended to provide a better grip for applying the compound to your strop.