Geometric Triptych

Geometric Triptychs are the items required to activate Gateway Engines and Gateway Portal.

Source
Geometric Triptychs are created within the Gateway Engines by placing a specific Resource in one of the three slots. Each planet requires a different resource to obtain the Geometric Triptych. The Gateway Engines can be activated with the corresponding Geometric Triptych created on that planet, while Gateway Portal requires one of each Geometric Triptych to activate.