I am posting this because it has good aesthetics, is sturdy and robust, and is simple, so many people can build it. Also, I think it would be cool to see more planes and rockets on this weapon-infested site.
This is a deliberately simple plane, so it will be very easy to mod. On the last step, I will show you a larger six-engined variant, although it is uglier, skinnier and rather cumbersome. This model is much more refined and shaped better. Feel free to post a photo of your model below, It would be cool to see this in original or full metallic colours!
Lastly, would people like to see more of this kind of stuff? (i.e not guns)
Step 1: Misc. Parts
Step 2: Fuselage
Step 3: Rear
Step 4: Wings
Step 5: Final Assembly
Step 6: Finishing Note
Here's a picture of a 6 engined variant. It has a skinnier body, no robot arm, two missile launchers at the back and an array of cannons along the fuselage. It lacks a robot arm, and the two extra engines have been removed. The engines can be slid off as they are connected to purple connectors. They clip back on just in front of the missile launchers (the two black triangular panels that are raised higher than the other engines. The fuselage cannons are the ball joint connectors on the blue rods. The second picture is the model from this instructable so you can compare the two.
Finally, why not build a hanger? I made 3 very small versions of this (twin engined), and made a storage tower for them. It was part of a huge moon colony I made, check it out here!