Dave:
It has been a while since I last built a DPM structure. I have attached a file that may help. I think I used Plastyruct Plastic Weld with no issues but can't be sure.
The most important thing I remember is having to remove the 'draft angles' from the sides of walls otherwise they would not fit properly. A sheet of sandpaper (80/100 grit), a good metal right angle like the 123 block to keep the wall square to the paper is all that is needed. A few swipes and you are good.
This is the first of 21 videos Woodland Scenics put out on DPM kit building - https://www.youtube.com/watch?v=1wd_ZI56xU4 Just beware with respect to glue the narrator is talking about HO kits which may be a different plastic then the O scale kits. If you don't want to go through the videos try the attached file.
Joe
