As a start I made a 2-dimensional design by hand, but it gave me much too little insight to work it out. I realized that I needed a 3-dimensional design, but it was almost impossible to draw, until I saw one of Greg Virgo’s You Tube presentations about Sketchup. An old version of this program (Sketchup Make2017) is free for use and ideal for this purpose. This is not the place to explain how it works, but I can focus on a few particularities. Special is the possibility to turn the design in all directions, it is easy to enlarge or reduce the size and look at it in all directions. The design can be made with an accuracy of mm’s and it is easy to adapt it. Furthermore the are circulating many You Tube instructions how to use it and how to make it your own. Apart from that there are ready-to-use designs which can be adapted according to your wishes and for specific vans. And last, but certainly not least, the process of designing with Sketchup gives you new ideas or subtle unexpected changes. It helps you thinking how your camper can look like, what the possibilities are, but also the limitations.

The link  to the download: https://help.sketchup.com/en/downloading-older-versions