There is six levels on Region 12 that you will need to get Gold medals on. Here are some tips to help you achieve gold on each, this is how I did it, so although it worked for me, it may not be the best solution.
First shot - Aim for the 5k bonus icon and curve left, hitting the tower, explode your shot at the right time to blow up the tower in the back, as well as the red satchel on the left wall. This should completely level out the left side of the castle excluding the bridge. You should have a 2x multiplier and be extremely close to 3x.
Second shot - Aim for the right side of the wall, underneath the bridge and explode your shot at the right time to destroy all of the rest of the castle, and the right side of the bridge.
Third Shot - Hit the speed icon and destroy the entire castle in the back. You should now have 5x multiplier
Fourth Shot - At this point you should be close to hitting the gold, and there should be nothing left other than the remaining bridge on the left. Hit the 5k icon and destroy the rest of the bridge.
First shot - Aim for the two speed shots in the back on the right side. Extract all four mini shots immediately and hit the 5k icon on the bottom left of your screen and the 10k icon on the top right. Make sure your two outside shots hit the walls on the front of the caste and knock down the castle entrance, and your two middle shots hit the two speed icons on the inside. This should destroy most of the right wall and the back wall and give you enough bonus icons for the Crack Shot 2.0 achievement.
Second Shot - Aim your speed shot at the bounce icon and sway your shot to pick up the 5k icon and the 10k icon then power it right before you hit the wall and take out the tower in the back straight behind where the bounce icon was. You should now have eliminated the entire right side of the castle.
Third Shot - Take away the next chip as best as you can so you have an amount on the left that is doable with your next shot
Fourth Shot - Hit all three of the remaining 10k icons and extract your shots to hit the rest of the castle. You should now have a 6x multiplier.
First Shot - Aim your speed shot at the red bomb on the left of the front wall, activate the shot right when you are in front of it and it will go back and destroy all three of the towers behind it.
Second Shot - Aim for the castle to the right, right behind the metal plated tower. Activate the shot so that way it will hit the front wall and go back to destroy the castle, that way the red bombs on the right will explode, destroying the entire right side of the castle.
Third Shot - Aim your bounce shot up so it is in line with the remaining strip of towers on the left on the castle, make sure you take out all of them with this shot
Fourth Shot - Aim at the Hot Goblin, and hit the wall, exploding the bomb in a way so it bounces back to hit the tower closest to the front wall. The shot will bounce back exploding the remaining two towers in the back.
First Shot - Use your first ot on the grouo of castle in about the middle, right before the drop off the the left, blow up the entire middle part right there so you leave a bottom, and a left side.
Second Shot - Use your lift shot to get the Hot Goblin and curve right to destroy as much as possible down below, you should have no more than a couple of towers by the red bomb half way don't he drop off. This sounds hard, but those are the towers you will more than likely have left without even trying.
Third Shot - Use your shot to destroy the towers on the right that you have remaining from the lift shot.
Fourth Shot - Hit the left side, right on the front wall on the left, make sure you hit as far on the right as you can though. This will blow up the Red Bomb on the front wall taking out the far left tower and should bounce to destroy all the rest of the towers left on the castle.
First shot - Hit the left tower with the bomb on it, a explode all the archways on the left side of the castle.
Second Shot - Hit all the small towers lined up on the right side of the castle
Third Shot - Use the speed shot to take out the row on the right side, its very obvious, you cant miss it.
Fourth Shot - Hit the Hot Goblin and extract all the shots to take out the entire back castle.
Fifth shot - Hit anything you miss, you shoudl already have 6x multiplier and a gold medal at this point.
First Shot - Hit the second bounce icon, then extract your shots, hit the farthest bounce icon and get all the 5k icons. Then destroy the entire back castle.
Second Shot - Extract your shots right away and take out the entire front castle
Third Shot - Hit the entire right small armory type building and explode your shot.
Fourth Shot - You should have the gold medal by now, just use this for the scrap.