Corn is growing huge, oops!

With perfectly good intentions, I purchased seeds to plant in my mother's garden. She hasn't been doing anything as the last few years she isn't able to move around like she used to. Unfortunately I've not had as much time as I would have liked, and now it's August. MID August, almost. Fortunately for me, my parents are pretty awesome sometimes and they really just want the free fruits of my labor, so they said it would be okay for me to construct a makeshift greenhouse over their garden area. It already has a wooden frame around it, so it shouldn't be that bad really. The issue is I'm not sure what materials would be best for the job.
My boyfriend mentioned that he could attempt to build a green house, but I think I'd rather keep that one at home for myself. This one will most likely be with relatively found material as I don't have much money to spend and they don't either. Perhaps I'll attempt to do a kickstarter.org project and see if I can come up with a few hundred to build them a nice one. I REALLY want to be able to help my parents out in a good way.
On a related note, my spare bedroom is overrun with corn! I put the seeds in peat pellets thinking I would have time to stop by on a day off, but didn't get to. Now I have corn showing true leaves and growing almost sideways. I had to bring in another lamp in order to keep them growing straight. I do intend on growing tomatoes indoors this winter so it's kind of nice to see how my spare room handles it. I got my mom the corn that I links, and I think she'll really like it. I got it because it said it had a short maturity time, and I do only have 88 days until the expected frost. Like I said, I started late!! Hopefully I can get the greenhouse in time.