Well, i'm the exact opposite of you. I always have idea's, but when I try to make them, they fail. So off the top of my head, I can think of three. You should try recreating you're own house. I really like doing that because it's fun, and you get to understand you're home a bit more. My second idea would be to try to build an abandoned and destroyed village. This one's a bit tricky because you will need to build all of the buildings for the village [There's a build], then break some blocks of the building's so it looks old and run down. My last idea would be to make a baseball stadium. Now, this doesn't need to be baseball, it could be what ever you're favorite sport is. Personally, I like Hockey. This is a challenge because you will have to make it look authentic. They're is also a good part about making you're favorite sport's stadium, it will test to see how much you know about the sport. If you think this is easy, here's a few challenges to make it a little more challenging. For the one about recreating you're home, you're not aloud to look around you're house! That test if you know you're house well. Also, a challenge for the last one is to not look at a picture. Try to build one off the top of you're head! Hope these idea's helped you!
-uTurl