Hello,
Thank you for the welcome and the support.
I ended up googling more, and found something quite surprising:
http://www.petclassics.com/Dog-Potti...-potty.39.html http://www.composters.com/docs/petdigester.html#pdp
An indoor/outdoor grass potty for dogs!
There seem to be several versions. Most demand that you rinse the grass/synthetic grass to get rid of urine (which catches in a tray/container below, to be emptied) and remove the poop manually.
I think this might be the cheaper solution to building an indoor/outdoor kennel, then!
Thanks again,
mbfleur