In the Rapid Method, we don’t bother with learning to write Thai.
Firstly, you will very rarely need to write Thai by hand. And on the few occasions you might do so (e.g. to write out your order at a small Thai restaurant), writing Thai is essentially drawing. Just draw the outline of the picture you have in your head for the letter in question!
If you do ever find yourself wanting to write something in Thai, it’ll usually be on your phone or computer, sending a text or chat message or writing an email.
In which case, you will be typing the letters – which is just another form of reading Thai, after all.
Besides, trying to remember the spelling of the different words is quite difficult and you’re better off just accepting the way a word is spelled and focusing simply on sounding it out.
Nevertheless, as you build up your vocabulary and start to recognize similar-sounding words with different spellings, you will gradually get to remember how they are spelled and will develop a kind of visual memory of each word’s shape.
If you do find yourself wanting to write short messages or sentences then make sure to have a (computer) dictionary to hand and check the spellings of each word as you type it. You might be asking a question ไหม when you intend to say you have something new ใหม่.
Secondly, the act of composing or writing letters or articles is a very advanced skill, even in your own language. You only get good at it by reading a lot.
Anyway, a writing style is usually much more formal and uses a different vocabulary to the kind of language used in colloquial speech. And as the main aim of the Rapid Method is to focus on conversational fluency, there is usually not much of a reason to spend time learning to write (or compose) Thai sentences or letters or articles.
Nevertheless, if you study the more advanced texts, like Chuwit’s book about Thai politicis and some of the news articles, you will become familiar with more formal writing styles and vocabulary. And then, by all means, have a go at writing your own works if that’s what you’d like to do…