Take a look at earbud cases on Amazon. I ordered a few and found one that fits the Uni Pro as well as a few carts.
Just saw these over on Amazon. (Hope this is okay Mods) link: DSC-Mart Silicone Cover for Yocan Uni Pro Case Sleeve Sheild Skin Rubber Wrap (Black) https://www.amazon.com/dp/B09QSM6DSS/ref=cm_sw_r_apan_i_KMDJK1KT9F1FFD908YPT
They only come in 2 colors right now (black and white/glow-in-the-dark). Got a few on the way for my devices. Got the white one here first. Cases fit both the OG and the 2.0. I like the grippy texture.
That rubber piece is basically a gasket that holds the connector so that your cart makes a connection to the cart, I would recommend getting These from amazon they work well!
Generic Grav BROS Plug Mini Connectors Magnetic Ring Adapter for UN1, Chrome, 3-Pack, Silver https://www.amazon.com/dp/B09FKFCQMK/ref=cm_sw_r_cp_api_glt_i_HYTFJQKT3G7NT924EY8P these ones have better reviews and cheaper
Ant C Shop 3 Pack 510 Thread Magnetic Ring Adapter https://www.amazon.com/dp/B08X1HR3DV/ref=cm_sw_r_cp_api_glc_i_Z8KVQBB81QT6Y3BMG1Q3, I have no idea if these are the correct ones or not, I haven’t ordered them yet
https://www.amazon.com/gp/product/B08F6J71FL/ref=ox_sc_saved_title_1?smid=A23HA0AEY0089W&psc=1 is what we have it. I love it I can carry a few of my humira pens, one of my wife's emgality pens and still have room for the vape, carts, charger and all that keeping the medication cold for 2-4 days without needing a fridge.