Just received my under consideration stamp from MTT using Aus passport and embassy letter. On amnesty from a TR60, went to counter J (mistakenly had booked for counter K but it didn't matter) with documents as per Brian McCarter's post (cheers!). Virtually empty and everyone was very polite. Process took about 15 minutes. Due back in two weeks, immigration officer said just to walk in, no need for appointment.
TLDR : Answer Summary
The user shares their positive experience of obtaining an 'under consideration' stamp from Thai immigration using an Australian passport along with an embassy letter. They discuss the process of going to the correct immigration counter, which took about 15 minutes, and mention the friendly service. They are scheduled to return in two weeks but were advised that no appointment is necessary.