If you don't want to buy a third-party morphing plug-in, you can roll your own morph in After Effects using the Distort>Reshape effect.
Say you've got two layers , a handgun and a water faucet, and you want the faucet to morph into the gun.
You'll need to create two masks, one outlining the shape of the faucet and the other outlining the shape of the gun.
Assuming you've drawn the gun mask on the gun layer, copy it to the clipboard and paste it onto the faucet layer, so the faucet layer contains both masks.
Then copy the faucet mask to the clipboard and paste it to the gun layer, so that it also contains both masks. You may want to set your mask blending modes to None, to better see your layers.
Apply the Reshape effect to both layers.
On the faucet layer, choose the faucet mask for the Source Mask and the gun mask for the Destination Mask.
On the gun layer, choose the gun mask for the Source Mask and the faucet mask for the Destination Mask.
On both layers, set the Boundary Mask to None, and keyframe Percent from 0 percent to 100 percent over the course of a few seconds.
Finally, cross-fade one layer into the other by keyframing the top layer's opacity.