LibreCAD is free and opensource 2D CAD software.
Download from here.
apt install librecad
snap install librecad
In KDE the icons in the file dialog are not visible and application icons are not suited for dark mode.
Edit the desktop file ~/.local/share/applications/librecad.desktop and modify the exec key value as shown next.
Exec=env -u KDE_FULL_SESSION -u XDG_CURRENT_DESKTOP librecad %F
Using the GUI edit the LibreCad menu item replace Arguments field with -u KDE_FULL_SESSION -u XDG_CURRENT_DESKTOP librecad %F.