I’ve added (with much help from Simon Owen) SAM Coupé support to “BorderTron 3000”, my Border graphics editor originally for the Spectrum.
Unlike the generic version, this one isn't restricted to the limitations of the Spectrum. So it offers a number of benefits:-
It lets you draw pictures, and spits out SAM *.dsk files that draw those pictures in the Border area of your SAM.
http://freestuff.grok.co.uk/bordertron3000/sam/ - it’s a Windows executable, but it should be fine under Linux or MacOS with WINE.