, this is a small write up i did for someone else some time ago, it's roughly how i went about creating my Elm.
viewtopic.php?f=129&t=5600&hilit=+broom+elm
I found this pic of the 2 shoots i started with,,
first pic.jpg
. In the pic, you are looking at the rear of the tree,From memory, I made the V cut at a height of about 4 to 5 times the diameter of the trunk, It was made fairly deep( a deep v- not a shallow v)and slightly lower towards the front- of the bottom of the V(make sense?). I was lucky enough to have 2 minor shoots roughly in the right spots, so i made the V from those shoots down, keeping the cut close as possible to those shoots, so the cambium would easily start to roll down the cut areas..The V cut was also scolloped out(i'm sure u know what i'm saying) to allow for said cambium to roll and heal well done the cut..Cut paste was used. The 2 shoots were lightly wired to the correct angles(upwards and slightly out)to follow the flow of the V cut, then allowed to grow for a season. I in the following late winter the tree was repotted and the new growth was cut right back only keeping the main leaders on each side(1 on each side) and cutting them back so they were fairly short, so the new seasons growth would produce a new leader to train and at the same time give them taper and movement. Over the next few years the same sort of treatment only you can start to keep some side branches to start building the canopy:) Basically once you've gotten the V cut and new leaders starting to look OK, let it grow each season ,while selectively pruning braches to keep them heading in the appropriate directions, thruout the growing season. Eventually the tree will start to get it's basic shape and you can be more selective about which branches/new growth you want to keep or cut off.I always take shoots back to 1 or 2 buds- no more-as my tree is quite small and longer would not really produce the fine branching structure that i'm chasing,,. I didn't work to any plans or sketches or even any other Bonsai i had seen before, You could say i let the tree tell me what it want from me . The hollow trunk started with what i saw as a boring trunk so i first did this to it.
elm in its early days.jpg
. and after a while i felt that i may look OK with the split going from the hollowed out section right up to the forked junction. As luck would have it, it turned out better than anticipated
...One thing to keep in mind is the Finished height that you want your tree, you must think about that the whole time your developing or you may end up with an out of proportion trunk/tree.
Hope that helps some
, i thought maybe someone else may come thru with the methods they use, helpful lot 
