Hey, I've made a model placement script. I'm just wondering though if it's possible to make that model only collide with one other model such as the floor and ignore walls, etc... If I set the collision to false then when the player goes to place it, it literally just disappears due to falling through every model.
When you are placing the model, have all of the parts in it anchored, non-collidable, and raise the model by the model's height divided by two. This should keep it from falling while trying to place. When you do finally place it, make all of the parts collidable and you can do whatever is necessary to the anchor property.
Hope this helps, even though I provided no script examples. :)