After making and submitting 2 ship designs for the contest, here are some issues and wants with the Ship Designer.
Issue 1: Customs parts lose mirror properties.

This is how the part is supposed to look.

This is how the part looks after saving it as a custom part. If I try to mirror the part so it looks like it should, any other part I then attach to it acquires the mirror properties, which is not good for a part like this. I had to make the final custom part by creating all the pieces without mirroring. (I have mentioned this in previous posts, but trying to do detail work for the contest really brought these issues to the forefront.)
Issue 2: Wonky hard points.
Another issue previously mentioned:

The part at the bottom should have attached straight out from the part it is connected to. However, it acquires characteristics of the part it is attached to, which makes detail work painful sometimes. I would prefer that new parts not acquire the characteristics of the part they are attached to.
Issue 3: Can't delete custom parts.

Half of these parts are mistakes. I can't delete them. Please add a delete option.
Issue 4: Objects may look different in the game.
This is one of my new designs as it appears in the shipyard:

Everything looks as it should from the Ship Designer. However, when I build one in the game, the habitation rings are resized smaller. I can't figure out why.
Issue 5: If we create a custom part, we cannot then add something to it and create a new custom part that incorporates the original one. Again, when doing detail work, it would help to be able to create a base custom part, then add to it and save it as a new custom part.
Finally, a request.
Please, please, please allow us to copy parts. Again, when doing detail work, having to change the characteristics of every part instead of doing it once and then copying the part would really save A LOT of time.
For all the issues, designing ships is still a lot of fun!