You can actually find tutorials for DIY pasties. Also stickers work just fine, just avoid moisturizers. If you're not feeling creative, get on etsy and see if one of the sellers can custom make some reusable pasties for you
Im no LBTC member but I am the queen of improvising haha. Hit up some craft stores, you can even buy themed sticker packs on Amazon. I got a great pack of pin up girl stickers for my suitcase.
Not part of that group either, but black tape or any type of tape on Amazon should work they sell all size and color tape. You can also use x pasties and just give then a trim. Have fun
Might be something here that will work CRYSTAL BODY TATTOO SHOP by CRYSTALBODYART Nipple cover | Etsy