It all started when it became possible to build virtual LEGO models with fan created software like Ldraw. Over the years many add-on programs were written, to improve and expand the possibilities of the virtual models. High-res renders, flexible elements and semi-automated building instructions (BI) are just a few examples. If it wasn't for those we would never have had BI for some of those great TECHNIC MOCs (My Own Creation) that we see today. People like Nico71, Jurgen Krooshoop and Designer-Han build TECHNIC models and make BI themselves, whereas in other cases it's a collaboration, for example between Crowkillers who builds and Blakbird who makes the instructions.
Many fans take it for granted that those BI are almost always shared for free, and are discontent when someone dares to ask a compensation for it, but actually we should be very, VERY grateful for that.
Compare this for example with other industries: people pay a lot for sculptures and paintings; tutorials for courses cost money, besides having to buy all the materials yourself. So what is it then that makes LEGO creations so different?
Having a virtual copy of a LEGO MOC is one thing, but making step by step BI takes a lot of extra time and effort, especially when in our case we're talking about bigger TECHNIC models. Even though the process for making them can be done semi-automatically today, they are still far away from LEGO standards, unless...
Your name is Joshua Delahunty.
This life-long LEGO enthusiast has been active in the community from the beginning and is a software engineer by profession. After he had made a few smaller building instructions, late 2008 he came across Nathanaël Kuipers' modular ConceptCar and was determined to make this his next project. Because Nathanaël is a former LEGO TECHNIC designer, it would give Joshua a great opportunity to learn many aspects about how to create BI according to LEGO standards. His pursuit would be to develop and present BI as close as possible to the real deal. Little did he realise the very long and intense period that awaited him...
Why did it take more than 3 1/2 years to complete in the end?

First of all we must not forget that this has been a spare time project, and that this has been done besides all the day to day tasks, routines, and difficulties dealt with. But apart from that there were many other challenges to overcome.
Before being able to consider to even start producing BI, the model in question had to be built virtually. Nathanaël used MLCad for this, however, certain elements were not available in the parts library at the time. Philippe Hurbain another big LEGO enthusiast and Ldraw expert was called in if he could design those elements in CAD. Luckily he gladly accepted to help out.

Once the model was created virtually the biggest challenge in the whole process of making the BI was communication. With an 8 hour time difference it was not easy to find a slot to discuss the approach, ideas, model changes, etc. That's right, changes were made on the model during the BI process, as the ConceptCar was not fully designed with BI in mind, nor up to LEGO standards. Making changes on the go is time consuming and dangerous, because they can have influence on other parts, especially in TECHNIC. It's very common to miss something and have a mistake left in the update. This is probably acceptable for a MOC, but in this case Joshua had set himself a clear goal that those BI had to be as close as possible to official ones.
This leads to another major time consuming challenge; creating 'exploded' elements in steps for better visibility. As a consequence this means that not a single step could be produced (semi-)automatic, but every step, including sub(-assemblie)s, had to be created manually. This was only possible due to Joshua his dedication and persisting determination.
Because the process of making the BI had to be quite flexible too - remember there were changes on the go - the piece of code for every single step was saved. This is a painstaking job, and here the programming experience from Joshua was critical!
After the image for a sub or step was created and saved, the lay-out had to be done manually as well by using Adobe InDesign. Windows for BOMs (Bill Of Material) and subs were made, and the images of elements and steps were pasted in. This is not such a big deal for small models, but when we're talking about a model with almost 1500 elements spread over 200 pages of BI, this can be considered a major task!
Often it happened that there was a disagreement about the best way of building/ showing a step or section. Then there was a short discussion with argumentation on which way to go forward. Sometimes more than one solution was produced and then compared. Again this slowed down the process, but that's what you get with strongly opinionated perfectionists.
The end result however can be considered satisfying and a milestone in unofficial building instructions. The downside is that, because the process took so long, there is a good chance that the model is less interesting and possibly outdated by more recent MOCs. By presenting some teasers of the quality of the BI in this article , the developers would like to measure how much interest and appreciation there is for such projects. Is it worth the effort or more like overkill?