First of all, the 48" x 48" x 31" option is not 172 gals, it's 309 gals.  The item's description doesn't change when you select the bigger option.  As you can see in the photo, it is large...probably used best with a lot of leaves, grass clippings, and yard waste.  It was easy to assemble.  It took me all of 15 mins to put all the slats and spacers in.  On one rail, I had to use a hammer and blocking board while sliding a slat to get the groove smooth enough to put all the other boards in.  None of my spacers broke as reported by others but you do need to be gentle when sliding them in as they are thin at the neck.  You can make this composter bin by yourself but you'll need another person to move it so if you can build it where you want it, that's best.  It's a good price too.  It would likely cost a lot more if you tried to build it yourself by buying individual cedar slats and cedar posts.