Put the part flat on the board again. Leave it to dry for a few minutes. It should be quite firm before you trim it*.
Cut off the top part. Use a sharp, clean and dry scalpel**. Make the cut at an angle - see next photo. You can use the template as a guide (4) - it will show you where to start and end the cut to get the correct angle.
* If you make the cut when the paste is still soft, the body will lose its shape and you will not get a clean cut.
** If the scalpel is not sharp, clean and dry it will pull the paste down and you won’t get a clean cut.