The accessory sets are meant for existing resin or mold injected kits in which you have instructions and you are replacing icky part with supposed better 3D printed part. I avoid those “add on” accessory sets that are to provide additional parts that are not included in your kit just for the reason of no instructions on where there are to go. Navsource is only so good and usually very broad photos.

More importantly is the era of your kit. Floating on evil site is an extensive upgrade set of platforms for Nimitz CVNs. Beautifully printed parts. But do they belong on your era CVN? Now if the knuckleheads provided instructions one could take their 1998 CVN and bring it up to 2010 and that is if the 3D parts match the missing part. Most don’t as every CVN is different in platform shape and location. Certain parts you can easily identify and their placement like aircraft crane but the majority Nada.

Here is another issue.

I am presently doing the Dragon Virginia. I purchased the EV accessory set for it. Now I have instructions of placement. But here is the rub. The ABLs in the accessory kit are bland ABLs. The separate weapons set of ABLs that is also sold by EV are beautiful with railings, rungs and open and closed ABLs. Huh? Lesson learned. Now I just buy the accessories I wish to upgrade from mold injected or resin and I stopped buying the full accessory set. Money saved.

Chinese 3D printed ship models are a whole new level of frustration especially if you have 4-5 wafers of parts and no instructions. I recently purchased a 3D printed ship model. Thankfully I saved the instructions from other builds.

There used to be a website in which you could download instruction sheets. I have not heard it referred to or seen it in years. One could start their own business just selling instruction sheets.

My advice if the individual 3D parts are sold separately buy those provided you have existing instructions and avoid the accessory sets. Many parts I can not identify anyway. If you are going to build a 3D printed model you best have instructions from a previous build or very good photos.