In order to print accurately and avoid supports, each element should be printed separately. I glued them together with cyanoacrylate glue in pairs. 

(skadis_tamiya_10_1 with skadis_tamiya_10_2)

(skadis_tamiya_10_3 with skadis_tamiya_10_2)

Only for the holders (skadis_tamiya_10_5) I used supports, but you can print without them. Then I glued them to the modules in the prepared places.

To connect everything on the board, you don't need to use glue. In the pictures, I used colors to show more precisely how to connect them.
skadis_tamiya_10_1 - yellow
skadis_tamiya_10_2 - green
skadis_tamiya_10_3 - red

Print the appropriate elements to expand it.