I haven't had a chance to show them to DP yet but have ear marked the kit for one, the robot and the wheel set. it looks great.
Meanwhile we trialed a few other ideas.
The velcro was a disaster, the hook and eye sides stuck together far more strongly than the sticky side so all that happened was they fell apart, tearing some of the packaging at the same time. I was hopeful at the time, and DS enjoyed sticking them on, but ultimately not satisfactory.
Double sided sticky pads were more successful but still not really satisfactory. Most of the packing is pretty uneven, like the sides of an egg box for example (rather than the flat top), so don't give a great surface to stick to. These did at least get the robot together although it wasn't really strong enough to play with afterwards.
Card slots is what I've done a lot of in the past. DS does get excited to see something being produced but ultimately wants to be more involved and it's too tricky for him to work out where the slots need to be or cut them etc. We've got a couple of fantastic space rockets made this way though that have lasted a LONG time and get played with a lot too. He also enjoyed painting and decorating them.