How to fill the empty room between vertices in a mesh?

Hi there,

I want to realize a pointcloud with a million vertices. The main task is to fill the room betweet each vertices when you zoom in to show closed surface.

My first idea was to change the size of the vertices but this doesn't work. I tried it with this examples: http://www.kamend.com/2014/05/rendering-a-point-cloud-inside-unity/#comments and https://forum.unity.com/threads/dx11-psize-bug-please-help.383220/ .

Changing the size in DX11 should be possible cause https://github.com/unitycoder/UnityPointCloudViewer/wiki/Point-Size-with-DX11 also do it. But I can't find how they do it.

Now my second idea is just to fill the room in an efficient way. An inefficient way is to creat quads. A Million of them qould destroy my system.

Hvae anyone a good idea how I could realize it?