DWM Compile and recompile DWM with synth

Hi, im going to reinstall freebsd in my main system, and this time I want use dwm, dwm uses a config.h for configuration, then I need edit distfiles and build my "edited" version.

My issue is, how can I make this with synth? I want use only synth for ports, I found threads like: https://forums.freebsd.org/threads/7816/

I saw this diagram in synth git project: synth diagram

Then, I understand that if I use "make fetch" to get the sources, then edit them and put it back where it was, synth should build the distfile that I have edited, right?

Thanks you.
IMHO x11-wm/dwm is so small and simple that there is no need to install it via ports.
E.g. I have a local source with my modifications for 10 years or so, and I don't want to touch it anymore.
Dear -Snake-,
I do the steps as below using ports-mgmt/poudriere. I am sure that it works with ports-mgmt/synth, too.
cd /usr/port/x11-wm/dwm/
make extract
cp work/dwm-6.1/config.mk work/dwm-6.1/config.mk.orig
cp work/dwm-6.1/config.def.h  work/dwm-6.1/config.def.h.orig
make patch
The you have the working directory /usr/ports/x11-wm/dwm/work/dwm-6.1 populated and you can modify config.h to match your needs. When everything is file do
cd /usr/port/x11-wm/dwm/
cp work/dwm-6.1/config.h  work/dwm-6.1/config.def.h
make makepatch
make clean
The output
# make makepatch
Generated patch-config.def.h
Generated patch-config.mk
The previous patches have been placed here:
shows why files/config.mk should not be forgotten. The next time x11-wm/dwm is handled by the tools your changes on the configuration are applied, too.
# svnlite status
?       files/patch-config.def.h
finds the unversioned patch which does not hurt. Baiscally the procedure is described in https://www.freebsd.org/doc/en_US.ISO8859-1/books/porters-handbook/.