Here is the step-by-step construction of a shape made from 2 Lobel frames placed in opposition, as presented in this topic.

This one starts from a heptagon.

Apply exactly the same approach if you want to start from a triangle, a square, a pentagon, a hexagon, or even an octagon (for this latter, you will have to place larger spheres at the ends because the angles are too closed at the junction of the 2 Lobel frames).