Without doors, I would consider this a studio apartment.

Look at Intel headquarters, Amazon, FB, Honda, Google, Nationwide, etc. 

My previous boss and mentor had two studio apartments that were sitting vacant for a long time.

And it also has a manufactured home and a small studio apartment on the property. 

Multiple, billion dollar companies are investing heavy in our area, such as Intel, Google, and Amazon.

I've mainly looked at Home Depot/Lowes for flooring and larger items and got hardware like knobs, faucets from amazon/wayfair but curious to hear where you all get your materials fromAlso, need to get a double vanity for master bathroom, any recommendations?

An example of not recession resilient would be a karate studio or hair salon, things consumers cut back on when times are tough (and now you, the property owner, aren't getting rent, and thus might have challenges making your mortgage payment).

Do you find the return is better with the studio size? 

It's usually around $15 on Amazon. https://amzn.to/3VKVLLP He virtually walks you through this step by step, and it's a great resource if you have questions later and don't want to go back to the forums.Second, as a Realtor and investor in Illinois, I agree with everyone.

Specifically, there's job growth (Intel, Honda, Amazon, Nationwide, etc) and the population is growing (unlike Cleveland or Cincy).