Hi Ramon,

> Also, how can I blend the surfaces of the (blending.3dm)?

You've got several of the original construction curves in there - in order to do a surface blend you need to pick edges of the surfaces but that will be difficult in your model there directly since the original construction curves are overlapping right over top of the surface edges.

So hide or delete those construction curves to get them out of the way and that will make it easier for you to select the surface edges to blend between.

- Michael