Getting hit in a gummi mission reduces your "score level", so it is best to never get hit.
This can very easily be achieved with the donut ship design.
You simply build only on the outher edge of the designer.
In the end you should have a donut (or pipe-looking) ship which can automatically dodge any enemy shots without needing to move.
Weapons, Cockpits and Thrusters can be put into the blocks that build the donut shape.
Normal enemy attacks and even boss attacks can be dodged automatically, but explosions can still hit your ship (or the cannonballs from the haunted ship mission).
The design in action: