<p>Plastic is used in 3D FDM/FFF printing partly because it had a wide temperature range for its glass state - where it can be flowed with some force, but won't flow due only to gravity.</p>

<p>Most metals have a very narrow, or non-existant, glass state.  They transition from solid to liquid with almost no flowable-but-not-liquid state.</p>

<p>Are there any metals or alloys that display a glass transition state?</p>

I"m no expert on this, but the article at
https://en.wikipedia.org/wiki/Amorphous_metal
may be relevant for you.
There are some special alloys, such as gold/silicon and various titanium-based ones, that become "bulk metal glasses" if cooled extremely quickly (for example, by sputtering onto a spinning cold surface). The speed of cooling prevents crystal formation. Early BMGs were quite strong but brittle; improvements have reduced brittleness and required cooling speed.