Turning a point cloud into an extruded mesh

Hello everyone,

I have a point cloud with about 6milions of points and I would like to transform it into an extruded mesh in order to apply a Boolean difference on it.
However, when I make the mesh via a patch, it is impossible for me to extrude it in order to obtain a “volume”
I put the point cloud as an attachment, could you take a look and try to extrude it on 1 or 2 mm?
The file is too big so i put the wetransfert link WeTransfer - Send Large Files & Share Photos Online - Up to 2GB Free

Thanks in advance

Try Shrinkwrap in Rhino 8