Ok, this is a big one...

My suggestion is to implement an option to allow people to create their own TARDIS exteriors. For example, if someone wanted a green TARDIS, or perhaps someone likes the scratches on the WAR Doctor's TARDIS but prefers the windows of the 12th Doctor's, My suggestion would allow people to mix and match components from any TARDIS to make their own unique exterior.

I know this would be a big thing to put in the mod, and for obvious reasons, it wont work on all exterior option (ie, you cant have Police Box doors on the Pokeball exterior)

Perhaps, to start off, only the Doctor's Police Box exteriors can be mixed and matched. players could swap between windows, toggle the St. John Hospice sign seen on the Copper and Toyota doors, toggle the scratches seen on the War Doctor's TARDIS, and set a custom colour for their TARDIS. 

It would be pretty cool to see what people come up with. maybe we could see pure white Police Boxes, or ones with Doors of the 1st Doctor's TARDIS, but with the windows of the 12th, and the scratches but wiith the St. John Hospice sign too!

As for How the player would create these custom exteriors, perhaps a GUI could be added on the TARDIS Monitor with the options. maybe it could look something like this...

Windows-> Toyota

Doors-> War Doctor's

Shell -> 1st Doctor's

Sctraches? -> Yes

St. John -> Yes

and the outcome...

Maybe they want a Red TARDIS...

(Very quick Photoshop. The actual GUI would look a lot better than this (hopefully), this is just so you get the gist of my idea)

To Be able to make a custom TARDIS, the player must craft a blank Chameleon Circuit, insert into the Chameleon Circuit panel on their console and when they Select

'Custom' in the available exteriors, they will get the option to change aspects of their exterior

Perhaps, as a limit, the player can only choose from aspect of Police Box's they've already unlocked by crafting the chameleon circuit.

So, basically, the player can only use the Toyota windows, doors, shell, etc, if they have already crafted and installed the Toyota chameleon circuit cartridge 

If implementing a whole GUI is too difficult, maybe this same Idea could be made on the SWD website. Similar to how you buy exterior, there could be an option to Build an exterior, which could give that Minecraft account a free Custom Chameleon Circuit cartridge labeled 'Custom'

I know this is a huge thing to ask for, and I certainly dont expect to see it any time soon, but maybe its something to think about.

Do you like my idea?

I think it would work well as gui but you should also be able to have more disguised Tardis's perhaps another feature would be to make an exterior out of blocks so it blends in when you land- or just have a working chamelion circuit option where depending on what planet you land on it changes to 2 certain blocks on top of each other- like the cobblestone or brick exterior

This is an incredible suggestion! It would be very cool in creative, maybe not so much in survival, or if it was maybe you would have to craft come sort of new component that lets you do it. Once you have crafted this component (diamonds, titanium, elec. circuits etc), perhaps you also have to craft a new panel to put this component into, like the Custom Exterior Panel. This does make it very hard to get in survival, but it would definitely be worth it! A fantastic suggestion.