How long does it take to get a non-immigrant visa stamp at Chaengwattana Immigration?

As this post seems to me, just for information but now starts into a discussion about work permits and visa applications in Chang Rai, I close the commenting. Sorry but to keep information clear make your own post. All Immigration Offices work a little different and when we start to mix different visa's, Extensions of Stay, Work Permits in different parts in Thailand in one big topic, nobody will get a useful answer.

Can you get a Non imm O visa being over 50 inside Thailand or do you have to leave and get one outside the country ??

If you're eligible to apply - they'll accept your paperwork and it "goes under consideration" while they process it. Return on the given date and get your stamp.