You are basically done with this paper house in last step. This step is a summary of some optional further steps to take:
Since one cell is a dummy, the voltage supply is not really enough to power up up a blue LED fully when resistant of conductive ink is taken into concern. Since the LED I used can sustain quite a high current, the house will be much brighter if I can add another solar cell and boost voltage up a bit.
The two LED hit each other when the house is flattened. This not just hinder the house from flattening, but stresses the fragile solar panel. If a flatter bright LED could be sourced and the two LEDs are offset from the middle line a bit, the house will lie flatter. This will also light up the house better.
To prevent the fragile solar panel from damage, silicones or 2-part epoxies are nice candidate for encapsulating the solar panel. You may dome the solar panel if you have no intention to flatten the house again. Alternatively, ironing an EVA sheet under a PET sheet will also be a nice encapsulation method that offers some protection to the solar panel. The house may still pops up if you did this carefully.
This paper pattern was originally designed to be a pop-up house. Although, this version cannot completely flattened due to the LED thickness and the fragile solar panel, sticking a folded card with the fold line aligned to that of the house's floor will make it a semi-pop-up house. The house will lie as flat as the flat LED you can get.
That's it. Hope you enjoy this paper house and my first instructable : )