Here is a website that will let you put up to ten characters and preview what they look like as tensho characters.
Next time, it might be a good idea to start a discussion about the various styles of kanji writing, since this is the Kanji learning forum. Tensho (篆書) is one of the several styles of kanji, and is most often seen on inkan (name stamps). Also, 黒 probably wouldn't be read as "koku" by itself; it would be "kuro"
more info on 篆書 here (Japanese) and here (English)