My shodo teacher Tony Skeen just published a couple of reference books that will help those looking to make inkan (seals). Both are intended to be used in tandem with the New Nelson's Japanese-English Character Dictionary.
The first volume is to help people sound-out their (non-Japanese) names in Kanji. There are choices--you can go by meaning, but then the pronunciation will be completely different, or you can go by pronunciation and find comparable kanji--THEN you have to watch for the meaning and also double-check to make sure it doesn't have some slang meaning in Japanese that might be embarrassing. So this first volume is a list of kanji by sound, in English alpha-order. Choosing Kanji for Use on a Seal Stone
The second volume has brushed tensho-script examples of the kanji from the first volume, both as normal and also in reverse (which is how you would carve it to make a seal). As far as I know, there is no other English-language resource on tensho-script that is this detailed. Tensho Kanji for Making a Seal Stone
Both of these are meant to be used in tandem with the New Nelson's Japanese/English Character Dictionary. Nelson's is one of the best J/E Kanji Dictionaries available. Here is the Goodreads link to it. They have it listed new on Amazon for $44 dollars, but seriously, shop around. I found mine new on Ebay for $18, and sometimes you can find it for even less! The New Nelson Japanese-English Character Dictionary
. NOTE: Be sure and get the latest version, so the numbers match up. Also, it's much larger than the original.
I've been studying shodo with Tony Skeen for over a year now. He's a certified instructor through Nihon Shuji Kyoiku Zaidan
and has been practicing shodo for over 20 years. The books are pricey, but he's not making much of a profit--the cost is mainly due to the books being self-published on small print runs.
He let me look at the proofs when he was working on the book and the books are very to-the-point. He just wants to make it easier for people to make better inkan. The online sites that offer to create tensho often use a computer font. These are HAND BRUSHED examples.