I have thought about it, but that is as far as I have got. My thoughts are a custom finial design, standardised across my range (this is part of a different, longer term plan).
I don't think that it would be worthwhile spending long on trying to brand a standard kit pen- the opportunity to do so is limited. If you customised the kit, the opportunities may present themselves. For example on a closed end pen, you could have a custom finial where segmenting gives you some repeatable options (e.g. the mont blanc star). Alternatively a signature centre band, clip etc.