I don't know how to put this delicately... but to be perfectly honest with you if you NEED plans to build a stand for a 55gallon tank then IMO you don't possess the skills necessary to build one...
I couldn't agree more.... 2x4 frame wrap in plywood then paint or stain to your liking.... its really simple... me and my friend took 10 2x4x8 boards and made a stand for my 90 you could park a mack truck on with no plans...