A few of these suggestions have probably already been brought up but here is my list of things I would like to see added to the designer.
1.1 The ability to flip the entire ship 180°, and I guess 90° for that matter. For those occasions when you have accidentally build your ship backwards. While your at it might as well add the ability to rotate the ship in any direction. I guess an "easy" way to do this would be allow the user to interact with the starting square that is used with all ships. That way it would also allow you to do cool things with it, for example making a Borg cube slowly rotate around.
1.2 The addition of a Gizmo cube or similar, like you get in 3ds Max. This allows you to always know which direction the ship is facing, as well as being able to easily jump to a side view, top view, ect with just one click.
Edit: This was actually in galciv2 so even more reason to add it! (Top right corner)

1.3 Similar to the suggestion above, you are unable to rotate your ship in order to look at it directly from above, below or either side. The camera seems to always be restricted to about 20° off keeping the ship on a permanent angle. If you could remove that restriction and give us full 360 rotation of the scene that would be great.
1.4 If I make a new ship design I can't use that design in another save unless I start a new game. Apparently this is because all the ship designs are copied over to the new save so if you share your saves all the designs are still there. Is it possible to have an import design or similar in a already active game to address this?
1.5 As there is no 'scale' marker when designing ships, you could make a small ship with giant or scaled up parts. Each size hull does actually scale the ship up and down in a minor way dependent on the hull. However if for example you make a small hull ship with parts scaled up, when on the main galaxy map these ships can take up an entire hex where smaller ships normally should be of a reduced size within the hex. My suggestion would be to have an option in the designer that lets you adjust its global scale, so you can easily reduce or increase its size. Changing how it both appears in a hex, as well as in battle.
1.6 Would be nice to be able to turn off in the designer the ship engine trails for specified ships. Some of the ships I made have the trails coming out of strange places, or if I design a ship without a traditional engine it looks really strange with a jet of color pouring out of it. I think part of the problem with this comes from If you hide ship parts such as engines, it dosnt also hide there particle effects.
1.7 Would be awesome if we could get some more uniform ship parts to help build ships by using their shapes as a base. What I mean by this is having some basic shapes such as a prefect triangle, a pyramid, a trapezoid, Truncated Square, Truncated cone, things of that nature. There are already a few but more would be great! Although once we are able to easily import our own 3d models, if that's still planned, there wont be much of a need I imagine.
1.8 There is an issue where you cant zoom in enough on some ships if your using small parts or parts all under the default 100% scale.
There seems to be a minimum Zoom in scale within the viewport, I presumed based on hull size, which means its near impossible in some cases to zoom in at all preventing you from adding a part to specific nodes or being able to more easily add fine details.
Likewise in some cases the opposite happens if you have a ship with parts that are to large. Were you cant Zoom out enough to clearly see the entire ship or rotate around it effectively.
1.9 Unless its already added somewhere, the ability to 'Lock Down' a part. What happens all the time is I either accidentally rotate or del the wrong part, or cant add a part to a node as another part is in the way. If we could lock down parts, effectively preventing any interaction with them or use of there nodes, maybe as two separate functions. It would just make things easier overall. Im thinking a simple Lock icon next to each slider that toy can lock individually, as well as a lock all, and hide nodes option.
Ideas I know for sure have been mentioned before:
2.1 Ability to easily change the hull size of a ship template without having to start from scratch.
2.2 Ability to change ship designer view port background. Allowing us to better choose a background that lets us see the ships better when designing. I remember reading you can easily do this by just replacing the background image in a folder somewhere but being able to do this in game would be nice.
2.3 Undo button for mistakenly deleting a part or changing one of its values.
2.4 Out of game ship builder that can just be accessed via the main menu.
2.5 Fix the 'Edit Mirror Axes' button, it dosnt seem to do anything atm as your unable to actually move the position at all?
This is the original post with the next two below suggestions, just copying them here to get it all together.
https://forums.galciv3.com/471707/page/1/#3590160
2.6 This has been brought up before, but when in the ship designer it can be extremely difficult to see your designs when looking at most angles, specifically looking under the ship. The Light in the scene really needs an option to stay fixed and not rotate when you rotate the scene so your able to better light areas of your ship. Currently you either get blown out bright lighting at some angles, or more commonly you get an extremely dark underside of a ship. A brightness slider for this light would be fantastic option to add as well. I know it can depend on what textures the ships are using however this really shouldn't be an issue no matter what you choose. Likewise, if the texture is the main culprit then we need to be allowed to change in game in the options the colors of the ships after we have already started the game. That is if the lighting issue isnt going to be looked at.
2.7 In Galciv 2 you could click on a part in the scene, then click a part you wanted to use from the panel. Then by default it would remember all the settings for the previously chosen part and make them the same allowing for easy duplication of a part with its settings. However atm, unless there is some setting somewhere I am missing, when you do this same process and click on a part in the left menu. It just goes to the defaults settings. This means you have to then go in and change EVERY setting manually of a newly added part. Clicking back and forth between the parts to make sure they are the same. It can become very tedious. If adding this is to difficult, a "copy/paste" all settings buttons would be great to be able to quickly do it for any parts you want it for.
There are probably alot more suggestions that I havnt thought of or forgot to add. But I think that's enough for now
!