The crankshaft and camshaft consist of many parts that are bolted together with bearings throughout.  This is the crankshaft and its parts.

And the camshaft and its parts.  This engine is interesting in that the boxer design allows it to share camshaft lobes between opposing cylinders.  In other words, there are 8 valves that need lifting and only four lobes on the camshaft.

Here is the case half with the through studs that hold the case halves together around the crankshaft.

The cylinder sleeves go onto outer studs just like the real thing.

The valves have valve springs to they move as the engine rotates.

The rocker arm has adjustable backlash bolts just like the real thing.

Here are some completed engine block pictures.