Grasshopper, extrude to point (with boundary)

heya, Im making a frame for a geodesic dome. Im very new to grasshopper and so bare with the messy work. I got my frames all sorted, wanted to extrude them to the center point but to a boundry like you can in rhino, but there doesnt seem to be this option. best thing i could come up with was to extrude them to point then to make an inner mesh and then solid difference them. is there a better less heavy on the computer way?