Fortunately, the law doesn't require one investment of 10M THB thus a combination is possible as long as one invests in:
The purchase or rent of a condominium for a period of no less than three (3) years issued by a relevant agency or government
The form of a fixed deposit with a Thai bank, under the condition that Thai nationals hold more than 50 percent of the shares
Purchase of government or state enterprise bond
If it's not possible to provide one of these documents, a letter should explain the reasons why. Note that all documents should be translated into English (in this case, the documents should be notarised by a diplomatic or consular service) or Thai.