I won't consider my 'production' a smörgåstårta mainly because the real thing looks much better and probably requires more work :p) but it certainly impressed the crowd when we brought it for the potluck picnic it was intended for.
All I did was to cut the sandwich bread to shape (it takes four slices cut into a quartered circle for one layer) and layer them with fillings of my choice.
Basically, (from the bottom layer), I had...
4 pieces of white sandwich bread, cut to shape
a layer of canned tuna (one can is just right)
a layer of sliced zucchini (about half a zucchini did the job)
4 pieces of wholemeal sandwich bread, cut to shape
a layer of sliced crabsticks
a layer of sandwich cheese (4 pieces)
4 layer of white sandwich bread, cut to shape
top decorated with a layer of creamed corn, shredded lettuce and cherry tomatoes