I painted these guys a few years ago.  Like all my Games Workshop Space Marines, these chaps have been painted but have never seen combat. I have never actually had a game of Warhammer 40K. Perhaps one day I should rectify that. Tech-Marines have some special rules that allow them to fix damaged vehicles and get them back in the game.

The Tech Marines with his Bolt gun and Axe-thingy.

A rear view showing his Powered Swiss-Army Multi-Tool that he uses to fix damaged vehicles.

Here are his two Tech-Servitors. They are a fusion of human and spanner.

To protect the Tech Marine cover is provided by these Gun-Servitors.  I am not sure of the exact rules around these guys but they seem a pretty cheap option for some heavy weapon support.

The entire squad together.