The enclosure I use for my geese is secure from predators and could work as a run. It is 20 ft long, 10ft across, and about 8 feet high. It is constructed of panels that are 10ft long and 4ft high. There are a total of 17 panels ( though it could be made with 11 if you wanted it to be 4ft tall).
Each panel has two 10 ft boards that are the top and bottom and has four 4ft long boards that are vertically placed to create frames (a 4ft board is placed on each end of a 10ft board and then the remaining two are are spaced to create three sections on the panel, which support wire/ fencing).
Some of the panels are covered with sheet metal sections to creat solid surfaces for the roof/shade and others have spaces left to place doors later. You don't have to use sheet metal and can just use wire too. Most of the panels will be covered in some sort of fencing ( I used kennel wire/ hardware cloth).
Six panels are arranged to form a rectangle and then screwed together. Another six panels are placed on top to create a higher enclosure and finally the five remaining panels are used to create a flat roof.
Doors can then be created wherever you left space for. I also place more wire on the ground surrounding the run to keep digging predators out; grass grows over the wire placed on the ground to help hide it).
I think this run would be large enough for 5 silkies and is modular so it can be taken apart and moved to another area if needed. If you are trying to cut costs down, (and only need 25+ sq ft for the 5 silkies) you could modify this design and make it square and 5ft tall and it would 100 sq ft (10 x 10) and 5 ft tall. You would only need to make 6 panels for this design and would just need to adjust the measurements. You could probably even make it smaller if you wanted.
I left a opening on the back end of my run to attach a coop also ( so a solid roof would not be necessary if you did this as there would be extra shelter in the coop).
I hope this helps and if you need anything clarified let me know.
