I've done several maps in a row now on Foundry that used most or all of the large objects (double boxes, fence boxes, and double walls) and take up a lot of the available space. On one I ended up with a very frustrating issue where as I was completing the map, I couldn't spawn certain things inside any more - the larger pieces would always spawn above the roof, because forge couldn't find space for its usual dramatic swoop-in spawn. I have two suggestions for dealing with this now that I've learned the hard way: 1. If you know you're going to use all the big objects (fence boxes, for whatever reason, are the most seriously afflicted with this problem), find a free area that you're not going to put much of your map in, and spawn a pile of the objects there. On my latest one I wasn't using the Foundry default bases at all so I made a stockpile of double boxes, fence boxes, and other large pieces like bridges and stairs there. Then I could just take what I needed later on, even as the map crowded the available space of Foundry. 2. One problem object can be bridges, which also like to start spawning outside the map as you eat up a lot of the space inside. I noticed that the Foundry ceiling actually has gaps in it - they aren't windows, they're just open cages or something. So with some careful maneuvering, you can actually get a bridge that spawned above the roof to slip through it and come inside where you need it. This may apply to other pieces as well, but boxes and the like will be much too large. It works perfectly with bridges though. Just tilt it until the front end slips through one of the large gaps, and then pull.
Another, possibly more cumbersome, way could be to set some of the area that is blocking you to not spawn at the beginning of the game. It wouldn't always be practical, but if you had, say, a wall that was blocking you and couldn't spawn your cage box where you wanted, you could set a couple of items in the wall to not spawn at the start of the game. Then you could restart the round, and it should give you enough time to place whatever item(s) you wanted. A riff on the 'interlocking objects' principle.
That's a great idea, I hadn't thought of that. Thanks, I will surely have a situation or two come up where that will be useful.
I doubt there's anything they could do with that. They've got other, more pressing things for them to deal with.