moostik [1] filed a deletion request for k3dsurf [2]: Replaced by mathmod-cvs, by the same author, using qt5: https://aur.archlinux.org/packages/mathmod-cvs/
[1] https://aur.archlinux.org/account/moostik/ [2] https://aur.archlinux.org/pkgbase/k3dsurf/
