Join my community SMP server! Oldy SMP is a small, modded survival world with a 500x500 border to start, and it expands by 100 blocks every week so the map keeps growing as everyone plays. Because the border is tight, resources are limited at first, but there are still plenty of ways to get what you need inside the square.
We also do Wacky Wheel Wednesdays, where mod suggestions from the community all go onto one wheel and a couple get picked each week. That means the server keeps changing over time, and your idea could actually end up in the game. Border expansion happens on Tuesdays, so there is always something to look forward to.
If you want a small, down to earth SMP with a funny, friendly community, this is the place. DM for the invite and details, and check the for the modpack too.