I just came across this source of lararia found on a shipwreck in the 1980s. The ship seems to date from around 20 BC.
The small temples are made of metal and in other respects are similar to lararia found in Pompeii. There is evidence these particular shrines were mass-produced using pressed argentiferous-lead plates joined by interlocking points.
The cellae doors open, containing the image of a deity: Venus, with Priapus or a trophy of weapons, and Mercury, with a bag of coins.
I wonder if this was cargo or if these shrines were for use by the sailors. I tend to lean towards the later as they were found with devotional images inside.
This is interesting for a few reasons. It shows lararia were constructed of all sorts of materials. We have evidence of wood and stone used in Pompeii. This demonstrates they were also mass produced in metal as well. It also shows these shrines were used well outside of the home on transport vehicles. I think all these assumptions have ramifications for cultores today.
Great discovery! This answers the question about portable lararia that can be used when travelling.
It also gives approval to the mass produced lararia that are on sale in the Internet these days. And it shows how important it is to have a lararium for your worship, not just a statue or image on an altar.