Make a new actor blueprint. Add a Static Mesh Component. ALSO Create a new variable of type **Static Mesh (Reference) **
Make sure you click the eye to make it public so you can change it in the scene view.
Setup your construction script as follows (The Static Mesh Component CONTAINS an actual Static Mesh so you need to set the static mesh within the static mesh component.)
You should now be able to drag in the blueprint and select a static mesh from the dropdown in the details panel.