I have a 3 month old veiled cham that is currently settled in in a 15 gallon tank. Most sources say that by now he should be in a much larger habitat. Unfortunately, money is really tight and I cannon immediately afford the upgrade for another month or too.

Will this have any major effects on my chameleon's growth and development? Furthermore, are there cheap ways to make your own cages?

Any input would be greatly appreciated!

he needs to be in a fresh air habitat...not an aquirium

Yes, your chameleon should have been moved into a much larger fresh air habitat by now. I know it's a bit late, but if you cannot afford a simple cage upgrade, you should not have purchased a chameleon. Housing is a minor cost compared to uv lighting and vet bills, not to mention long term feeding costs. In a month or two, your chameleon will be double the size it is now and will suffer significantly in that tank, if not perish.

That being said, a fresh air enclosure isn't all that expensive. Where are you looking at them? There are some very cheap sources online, and a suitable cage can be purchased for ~$30. You could build one from simple supplies found at a home depot for even cheaper. Whatever you do, do it soon.