Please add sloping walls to the Arena buildings. I love that building set, but not having sloping walls limits you options. Fence foundations would be nice too, although the Stable fence foundations don’t look too bad with Arena.
As a workaround, try combining other sets to replace the missing piece. Myself, i think insulatet wood and yamatai works well with arena.
Turanian also works well with arena.
I’m all for more building pieces.
Just to add, but exterior and interior walls should probably be part of the base game and DLCs as well. There was a mod that did this for vanilla pieces (I wanna say Savage Steel, but I forget), so when you’re using interior walls inside both sides look like the interior side. I don’t think they did the exterior version.
But that would help loads with the aesthetics. I’d imagine easy to do, just copy and paste one side to the other and add another entry in the item table and recipe table.
Glass Construction mod adds those I think. Or Emberlight maybe.