Double door or nothing I reckon! A single door pantry makes everything feel so cramped and that there's hardly enough space for my groceries.

seeking information and specs on black window/door manufacturers that would work in multi-seasonal house

I'm looking for a door lock suitable for a cavity slider that can be locked/unlocked from either side regardless of what the other side is. Sounds confusing???? Let me try and explain, and please see attached photo... we have a cavity slider between our main bathroom and our guest room (Bedroom 4), like a Jack n Jill bathroom or a Poor Man's Ensuite as they're sometimes known by, and I need a lock for it so that if there are guests they can have the door locked from their side but if someone else uses the bathroom it can also locked from that side.

I don't know what its composition is, but it feels cheap and nasty. It has turned fluffy at the bottom from moisture, and the actual door itself is a strange sort-of rough texture. I would love to be able to smooth it all over with something and paint it. One step further, I'd really love to be able to make vertical lines down it to resemble the third photo I've attached - what tool(s) would I use for that. Can some clever person(s) advise me on how to get started? Thank you so much!