On Sun, 13 Jan 2019 21:58:09 +0000
wrote:

I need to sink some boxes and cut a few chases in a plastered, solid,
wall. Previously, in modern houses, I've used a bolster, SDS chisel
and drill but this house has lime plaster which is very easy to
damage, so I was thinking of trying a diamond or carbide blade in my
Bosch multi-tool.

Has anyone who has tried this got opinions about whether to use
carbide or diamond, or any other suggestions?

In haired lime plaster you can cut the outline with a Stanley knife then
remove the waste with e.g. an old wood chisel.