This is just an assumption, because i've never done it. But I'm assuming you need to geomerge through the walls that lead to the back hallway first? It doesn't seem too hard. I rarely use that hallway though. Edit- Sry bro,. Edit again-god i'm amazing lol
check linubidux's map pankration or something like that...I believe he uses it in there That's what it should help....also, ask him, because in his new map square circle, he geomerged a fencewall perfectly into the bases of foundry
I really haven't gotten to geomerging in the back hallway in foundry. You should ask Linubidix. I know he had some sweet geomerging in the back hallway in square circle and prankration(some of his maps). I know he is really awesome in that category of geomerging.
You geomerge it like you would anything else. Place the box(or whatever you need) on the platform infront of the back ally. Put teleporters around it, then push it in with the door method. You're going to need to push it in all the way through the wall, and it may take you awhile to get it the way you want, but it's very fun.
The door meathod is very hard to get right. If you do the newer method you will have much more success, i think i have a map with single boxes blocking the middle way through, and walls merged halfway into the doors to make a new look instead of placing doors in the way..if you want. -> Place a double box and set spawn time to no, place walls all around it. Start new round, place the box you want to geomerge in the wall braces, and then wait for the box to spawn, after it shoves your box through the wall save and quit, then start up a new game...Delete the box that is set to spawn at start: no, and all the braces aswell. Now you should be left with a messed up box geomerged in the hallway, just grab this and work with it untill its in the right spot, then save and quit for a finished product. The door method is near impossible for this.
This way works but is very inaccurate and if you want it to be a symmetrical map, it's pretty much impossible. One way I've tried is to use doors to push the object into the back halls first off. Then I suggest that you get outside the map in the back hallway area, and form a lock under the map. (Made of teleporters.) From there you can push the object that you want geo merged into the lock space and it should be right into place where you want it. You can form the sides of the lock with doors, but it's more inaccurate. It's a little similar to the movable object geomerging. Goodluck, it's almost impossible to explain, it makes sense though.