I think with the sealing, the problem is that you're pretty much just holding your mouse button most of the time, sometimes clicking it. This gets pretty repetitive quickly, it's not really hard and it's just slow. I think having a certain path that you need to follow to draw the seal would be cool. Purple could be just holding mouse button and following the path, red to click certain spots in the path and yellow maybe something like a toy catcher machine where you need to stop at a certain spot to fill a portion of the seal. With this there could also be differently sized/complicated seals with higher difficulty. Obviously it's a pretty big redesign but those are just some of my thoughts.