I am looking for a word to describe a system or solution that has been put together from pre-existing parts. For example if a computer company gets software from 3 different software houses and sells it together as a complete solution maybe with some integration work on their part. The company might even white-label the system/solution and the customer may not even be aware that the system has been put together from constituent parts. The word could be IT industry specific but it doesn't have to be.
I always thought the word 'turnkey' meant this but I have found that 'turnkey' really means the opposite (ie an off-the-shelf system) and bespoke is a closer word but a bespoke system implies to me that it has been created entirely from scratch to the customer's specifications whereas the word I am looking for is more like 'assembled' really but that seems a bit weak.
Usually custom adds a bit of flair and it conveys the idea that the package has been tailored in some fashion.
You could say a custom-tailored software package, a customized system, or perhaps an integrated solution. All of these imply that there were pre-existing parts that were tweaked in some fashion for the particular customers needs.
Kludge comes close—the original root meaning "clever", but it has developed into a pejorative term. I used the term in an article showing how existing parts could be assembled in ways to solve problems for studio photographers. There was no new research or design, just repurposing of existing components.
I've heard the phrase software package used for software systems that contain more than one softwares. If it's an integrated package of softwares and hardwares, then you could either use the term computer package or roll your own name.