Sisko

You could specify a mathematical or technical problem to be solved by the competitors. For example: An electric adder to add 4 bits to another set of 4 bits. Another funny idea would be to reverse engineer typical household machines and recreate them with bricks. A printer would be a good idea because you can transport the paper inside the machine using LEGO wheels.

The German supermarket real sells the LEGO Technic truck 8258 for 129€ (Amazon 157€). I'm not sure if I should grab myself a second one now or wait if it gets cheaper...

It may sound a bit arkward: Have you considered to convert the PDF files into JPG files and copy them to a digital picture frame? Maybe the resolution of these picture frames is a bit too low..

Compared to Kaufhof the LEGO store is really pricy. The biggest advantage of the LEGO store is the Pick-A-Brick wall. They also sell some special products like the VW van but I am not interested in these sets. @david: Kaufhof is quite popular for displaying toys they're selling. Another Kaufhof in the Rhein-Ruhr-Zentrum has a big LEGO city display with all current sets in it.

There is a LEGO store within the CentrO Oberhausen but the giant Unimog is at display in front of Galeria Kaufhof. They also have a neat little 3D Star Wars show.

I'm glad you like it I tried to build a Palfinger crane in a very small scale without pneumatics or prebuild LEGO LAs. But unfortunately it is impossible to get three axles (2x to lift and 1x to extend the boom) through a turntable if you have limited space... (I had one idea for this but it turned out to be hilarious ). Right axle: lift and lower the boom Left axle (with bush): extend the boom It is possible to extend and retract the boom at nearly any position because all of the four gears go in the same direction. This design was just a proof of concept. One nice thing to add: Both functions hold their position because I used worm gears as "stabilizers".

I took a different approach for my LA: I do not recommend to use it for heavy duty because the gears could slip. Maybe someone of you can use this as an inspiration