Building a pc on your own is a way to control every part and every performance you need for your preferred games. Now, I have seen on multiple forums people asking if they can build a gaming pc without a case or not.
My personal view is that you should always use a pc case and for that you can check this guide (url). On the other hand if you want to get a case at a later stage and until then you want to test your new pc you will need a surface that is not conductive.
Other things to take into account are environment (that may affect airflow/cooling), people or cats, pets in general that could get their fingers into your pc. Also if you are clumsy and you use to smash things around a pc without a case is a solution for disaster.
Also having no protection against elements will end with more dust particles. Answer yourself if any component is delicate and you may decide to use a case eventually.
I know some think it will be great to see all the pricey components while you run your rig, but again what is the point of having all the expensive components and not protect them? Plus if you care about looks so much just go for a case with a window or a transparent case to show your lights and coloured cables.
So if you just can’t help it and you must have a no case computer assure: that you will resolve any cooling deficiencies in air flow, if there is humidity involved you won’t run the pc for long before it gets busted, grounding is necessary so a non conductive surface can solve a part of this.
I don’t know why I am searching for solutions on this. It is common sense to use protection meant for your hardware.
Still not convinced? Follow forum discussions for others opinions and experiences.