It would be useful if you could cancel placement of certain items when building a blueprint. For a small number of items it could be an alternate option to #1888.

Example, when building a composite blueprint and I don't have the last few items or the builder refuses to place them, deleting those items will allow the builder to go to the next section.

i think some way to edit blueprints ingame was planned?

I like this idea, my temporary work around is to just go far away and let the builder unload when it gets stuck, when I come back it has moved on to the next section of the composite blueprint.