This crocodile is my tenth alternative model built out of set 42106. It is my first pullback animal and it is also the best of alternative models from set 42106 in several areas: it is the longest (it is almost 60 cm long), the funniest, the strangest and probably the ugliest of them. :-) It features three wheeled chassis and when it goes it is opening its maw and moving its tail.

Truck features tilting cab over V6 engine with moving pistons and pullback motor. I am very satisfied with overall design and level of detail. It should be no surprice that I also had to sacrifice few features to get others so it actually can't haul anything because there is pullback motor in place where you would expect the fifth wheel and doors can't open in order to get rigid tilting cab. Building instructions can be bought exclusively from rebrickable.com where you will be redirected after clicking on "Download instructions". If you buy instructions for this truck you'll get instructions for pullback American truck for free and if you already bought instructions for American truck you'll get these for European truck for free too (you can find them on same place where you downloaded instructions for American truck).

This is the second plane I've built out of set 42106. It was inspired by planes from WW2 period and it is the most complex model I built from this set so far. It features pullback motor that is connected to landing gear and propeller. It also contains V6 engine with moving pistons. Building instructions can be bought exclusively from rebrickable.com where you will be redirected after clicking on "Download instructions".

Truck features long nose with grill and openind hood that covers inline engine with moving pistons powered by middle axle. It aslo features pullback motor, opening doors and optional flames from exhausts. Building instructions can be bought exclusively from rebrickable.com where you will be redirected after clicking on "Download instructions".

Buggy is my smallest model from set 42106 - it uses just third of its parts. It features pullback motor and custom suspension built without shock absorbers. They were substituted for rubber connectors and hoses.

I've got several comments that I should build boat out of set 42106 so my fifth alternative model is this hovercraft. It is heavily inspired by set 42120 because I was thinking about getting it but then I changed my mind and built it from set 42106 instead. So my hovercraft features pullback motor connected to rear wheels (yes, there are four wheels hidden in chassis), rear propeller and fake engine with moving pistons. Front fan can spin too but it is not connected to wheels due to lack of gears. Building instructions can be bought exclusively from rebrickable.com where you will be redirected after clicking on "Download instructions".

When I was building this steam engine I focused more on functionality than its look so proportions are not correct but it really works. Pullback motor is connected to rear axle and it drives also middle axle thanks to piston-rods. Front axle with small wheels works just like stabilizer (I had to move driven axles too far to rear behind center of gravity and whole vehicle would fall on its front without small wheels). Finally I added optional flame on chimney (smoke would be better but I didn't find any in donor set). :-) You can see it in action in this video. Building instructions can be bought exclusively from rebrickable.com where you will be redirected after clicking on "Download instructions". Notice: It is important to connect crankshafts on wheels correctly (there is 90 degrees angle between left and right side of steam engine) to get model working properly.

Helicopter features pullback motor that is connected to both rotor blades and landing gear. So you can pull it back and then lift it up to get rotor blades spinning. Building instructions can be bought exclusively from rebrickable.com where you will be redirected after clicking on "Download instructions".

This plane holds pair of the first places - it is my first twin propeller plane built out of LEGO Technic and also the first plane with pullback motor. Pullback motor is connected to both landing gear and propellers so after pulling it back you can let it run forward or lift it and let propellers spin during flight.

Model of race car features pullback motor, front axle steering, opening hood and easily removable body. Steering can be fixed and pullback motor disabled for increased playability so it works in two modes: "pullback" with blocked steering and "steering" with disabled pullback motor. How to switch between modes is described at the end of building instructions (it is not necesary to remove body for switching between modes).