Colours and Palettes
The Restock Colour Palette is used for pretty much everything in the mod. An Adobe shared palette can be found here. Unfortunately I have polluted it with some other Near Future Suite items but still relevant.
Our colour choice should be broken down primarily using two choices: Roles and Manufacturers. Additionally, care should be given to Special Surface Types which can affect colour choice, particularly when looking at KSP post-1.4 variants.
Generally our parts should use colour to advertise their role. Though most parts sit with a uniform grey/white colour scheme, highlights are used to add visual interest in a number of categories. Here are some examples
Typically batteries will have a specific 
High power electrical parts should usually use 
Typically crewed parts will have a 
Electric propulsion parts have a call-out 
Probe cores are usually monochrome, and sport a single specific 
Probe cores, drone cores and reaction wheels can all share emissive red LED illumination.
Reaction wheels are a good example of using the 
In general engines sit with a set of greys, with particular tones typing together features such as ablative nozzles between several different engines. Engine highlights are tied to manufacturers.
Where Role doesn't provide enough distinction (eg. between fuel tanks, liquid fuel engines, etc), we can resort to Manufacturer differentiations. In this case we give all parts built by a given manufacturer a certain look and feel, and a typical colour scheme. Manufacturers we use include:
Base of 
Base of 
Base of
The KSP 1.4+ era introduced us to the misnamed Dark Grey/Orange surface variant type. In Restock we will capture this using the combination of 
Certain tanks and recreate the space shuttle's external tank/Delta IV rocket's iconic orange insulation and are baselined to use 
Specular level is used in Restock primarily to differentiate surface material types. Most Metal objects should have a base specular level of RGB: 166, 166, 166, and most painted surfaces at RGB: 64, 64, 64 . Variability should be used to simulate surfaces more precisely.