Specifically about orchid mantises (mantids?).
Yup.
mantises!
The reason a lot of experienced folk will recommend an easier species is that an orchid, while fairly hardy, has a narrow band of care regime it needs to stay in.
With this species, you wont know something's not right, until it's too late. And sometimes, the indicators are so subtle, you'll only notice when its at the bottom of the cage basically dead, or when its turning black from some kind of infection.
Now, I don't think orchid care is that outrageous. But be very analytical of the care regime you
need, not the beautiful vase terrarium with an orchid mantis that you
want. These are way poorly ventilated, and usually glass so you cant even drill them. A good rule for jars is no taller than twice the mouth's diameter. A better one is don't use a mason jar!
Keep it simple to start. A 32 oz deli cup with sphagnum at the bottom lightly misted. A poly-lined vented lid while feeding on fruit flies, then a full mesh when it's done with them.
When you feel the size merits a terrarium, I recommend something practical like an exoterra nano 8x8x8:
http://www.exo-terra.com/en/products/natural_terrarium_nano.php. You can go bigger, but I doubt you'd need larger.
Don't be discouraged. You'll love mantis keeping. Just think ahead and plan.
Here is an excellent caresheet:
https://www.mantidsandmore.com/lexicon/hymenopus-coronatus/
Welcome to the forum! 
