I read a reference to them in my Osprey book about German Police forces, but couldn't find anything more anywhere. What did they look like, and does anyone make such figures?

I guess you´re you speaking of "normal" police and not MPs?

there is a recent release from ICM:
https://armorama.kitmaker.net/news/15293

for further referenece Wikimedia is often a great help:

http://commons.wikimedia.org/wiki/Category:Police_history_of_Germany

I was thinking of the Technische Nothilfe-which may or may not technically be police, and they often wore the work uniforms described in the thread title. But thanks for the heads up!

Ok, these things are a bit complicated... and of course not that easy to sort out, as I havent found much reference...

The Technische Nothilfe was somehow Part oft the huge ammount of different Police Organisations.

According to the wiki they were sucked in the "Ordnungspolizei" and wearing their green uniforms, when serving out of Germany.
Some Units were directly assinged to Heer or Luftwaffe, I think we can assume that they wore their uniforms then..

I´ve found some interresting pics:

http://www.german-helmets.com/TENO%20period%20photos.htm

http://www.europeana.eu/portal/record/92064/F273C49BD19831A4616E648A64593052544C8F75.html?start=1&query=title%3A%22Technische+Nothilfe%22&startPage=1&rows=24

I´ve just copied the links, as there is a discription included...

so what do we learn from that:
If you cant find the twill uniforms, you can still use the normal wehrmacht or police uniform, add the special insignia and ready are your TENOs

The guy in the background of the second of Fabian's links is wearing the drill uniform. It seems to be a special design for TeNo (i.e. it's not like the Heer drill uniform at all, which has no readily visible pockets). The TeNo drill uniform was used for heavy rescue work, and it was white and shapeless, but with patch pockets similar to the Heer field dress on the chest, but none on the short skirts - the best way to depict it would be to chop a German soldier figure about. A "Technishe Nothilfe" cuff band was worn with it, and the TeNo eagle on the left arm.