I may be misunderstand the way the kitchens work but .. aren't all the custom kitchens basically just someone else's set of favorite OEMs?
I just use BuildOS, it has a pretty good selection of downloadable OEMs and I make my own OEMs for anything else I need ...
It takes a while to get all the tools together and get the hang of making OEMs but I think it's rewarding and a bit fun ... Also I think it's great to be able to inject all of your own settings/themes/skins into your OEMs
If you are interested, I can give you a list of the tools I'm using and a rundown of the basic process ... (at least as far as I understand it) ...