Basically, these days you have two options:
There is a shop to officialize
user-drawn addons now, so you could get the Shielupe as a custom without addons, then draw his addons onto him with shading, (or get someone else to) and submit those addons through the shop.
Alternatively, you can ask to have staff do the addon as part of your custom, in which case you would have to discuss with them about the price for that in addition to the custom itself. The addons are already drawn but the image is flat, so staff would have to shade it, and possibly redraw some parts if needed (I'm not art staff, so I'm not super clear on this).