Easiest way of doing nose trim weights is to make an dwg (cad-file) of the chunk and go to a local laser-/plasma- or water cutting work shop. They can plates in 5-10mm steel. As steel has lower density do you need a higher stack of plates to get the weight right, there are usually a lot of space for ballast in the LS-ships so this is not an issue.
If you do not have the skills to make the dwg file, just make a drawing in scale 1:1 on a paper and give it to the workshop. Most likely can the make their own drawing.