You can use DOP as POP without the fuss too. Just set up your contact printer with some projection paper (say Ilford MGIV) and the negative. Place it in the sun or under a UV light source. 10 to 20 minutes you will get a relatively strong image. However it does bleach back somewhat in the fixer. I haven't tried TF4 as the fixer with this, just Kodak Fixer and plain hypo. The plain hypo had a bit less bleach back.
The color you end up with will NOT be that of the paper under normal use. I found that MGIV was kinda peachy-orange, some old kodabrome was brown and Foma (sold as Arista Edu.Ultra) was purple with a touch of peach.
Also, didn't try any toning in selenium or gold yet. Just did this as a lark a year or so ago and while it worked, I haven't made any plans to test further.
Hmmm... the post card exchange is coming up. Maybe I should do this for the exchange!