Side indicator, – search replacement for the cap ( spare part number)

Moinsen, at the K12 in the family the white cap of the side blinker was lost. Apparently a damage can not be seen. (picture) I took a photo of the built-in part and the cap of the other side. As original part is probably expensive, so is there something suitable from the accessory market? Maybe even the cap Solo? Found there some things (even as LED version) but if that fits then it is not clear to me. Especially since then both sides changed w I don’t have any interest in it in principle, if it would give the part for a small part. The lamp works without problems, I just need to see the white cover as in the picture. Does anyone have an idea? Evaluator in our needs has no K12 in the yard, where I could organize a cap for a few cents.