Part to join two or more Tech Platforms, to make a bigger platform.
To make 4x4 or larger you could put a octagon plate in the middle, between the other four and connect it to 61 SM plates

You need a 61x61 SM style tile to connect two of these, used a Bison hard plastic glue, worked much better then superglue.
Lowered it into the plate to print like the original parts, can be printed standing for better stability when placed.
PLA 0.15 mm layer height

Update: added a connected plate
19.05.2026. new extension model, pipe adapter for the the big fuel tanks

Will update as soon as I print this and more platform parts