I'm a small youtube I go by Alucard or dragon but is it possible you can make me a really big lab but that really amazing to 😊

You could build:
Library, lighthouse, city, harbor, warehouse, supermarket, recording studio, tower, prison, ruins, castle, fortress, statue, terracotta army, eifel tower, house, space ship, villa, London tower Bridge, something out of a movie, hotel, restaurant, skyscraper.

I'm sure that I've missed one of two buildings ;)

If you want to build something I have a couple of ideas for, you could build a mansion, you could start a super base (gigantic base), you could make something out of redstone. The possibilities are endless

I need to build a giant hollow purple-black sphere, approximately 100 blocks in diameter and 3 blocks in wall thickness
need something that looks like a organic cell nucleus, becuz i'm making a parkour on this theme

I'm in 1.12.2 so don't use things like coral
Don't bother yourself to build something inside, i'll make it myself ^^

Keep in mind all of my builds are done on Singleplayer so if u need a multiplayer build you need too pm me first.