One of our members sent in a full set of build photos for the 42108 Mobile Crane MK II, from the unopened box through to the finished crane with the boom up. I love that sort of thing.
A single finished photo is always good, but a build diary tells you more. You can see the chassis coming together, the bodywork starting to make sense, the boom sitting off to one side before it is fitted, and then the whole machine finally standing on its outriggers. It is the closest you get to watching someone build it without standing over their shoulder asking annoying questions.
The 42108 is a proper Technic crane. 2,606 pieces, yellow and black bodywork, full 360-degree rotation, extending outriggers, hook and winch, and a pneumatic boom controlled by a hand pump. No motors. No app. Just air pressure, gearing, and the patience to build the system correctly.
That is why I like it.
Mobile Crane MK II
CONTROL+ sets have their place, but there is something satisfying about a manual Technic function where you can trace the whole mechanism from your hand to the movement at the other end. With the 42108, you squeeze the pump and the boom moves. You wind the gear and the hook drops. You extend the outriggers and the model suddenly looks like it has weight.
What you are actually building
The build starts in the right place: the undercarriage. That first section can feel a bit slow if you are waiting for the crane shape to appear, but it pays off later because the whole model depends on that base being solid. Once the rotating platform goes in, it starts to feel like a crane rather than a long yellow chassis.
The boom is the interesting part. Telescoping sections, pneumatic cylinders, tubing, and the hand pump all need to work together. It is not the sort of section you rush. Get a hose slightly wrong and you will know about it later. That is not a complaint. It is part of why Technic cranes are worth building.
The finished model has a good shelf presence too. The boom gives it height, the outriggers give it width, and the yellow bodywork makes it look like site machinery rather than a toy pretending to be site machinery.
Most Technic kits use gears, axles, or linkages to drive their functions. The 42108 uses air pressure. A hand pump built into the model pushes air through tubing to a pair of pneumatic cylinders, and those cylinders extend or retract the boom sections as the pressure changes. Squeeze the pump and the boom extends. Release the pressure and it retracts. It is a completely different building experience from a gear-driven kit, and for many members it is the first time they have built a working pneumatic system in LEGO.
Thanks to the member who sent these in. Build diaries like this are exactly what I want more of on the blog. If you have progress photos from a Brick Club kit, send them over. Finished models are great, but the half-built stages are often the best bit.
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