Okay, the first image shows the "medium" stage being selected.
Then we see this:
The grid is fully zoomed out. You can tell because the option to "Zoom Out" is greyed.
From here, we can see we have a 14x11 grid to work with. That's 154 squares.
If you measure the "Remaining Parts" bar, you'll see it's 112 pixels. The filled segment is 17 of that. Do the math, and you have 15% filled.
That means you can get 6.66 times more stuff before it's filled.
We got it filled to 15% using 10 blocks and 4 ladder segments.
Do some more math, and you'll see that we can have 66 blocks and 22 ladder segments before we reach 100%.
It's important we don't assume the ladders and the blocks carry the same value. Some pieces might be more "expensive" than others.
Using those numbers, you could build a stage that looks like this:
I wouldn't worry about not having enough pieces...