if the concrete is too coarse, know that it will cause blurring at the edges. Lastly, there's microtopping. A thin layer of cement and polymer is used to create a seamless surface that is smooth ...

Molded spherical concrete shells are a time-tested technology, widely used for commercial and domestic purposes. Seamless concrete is waterproof, fireproof, draft-proof, termite-proof, vermin-proof, ...