The bends are done by heating them. You can either use a small butane torch or a heat-strip(safer) and can get either from an acrylic dealer.
The thing I have heard is that you should only put one side on at a time. This allows you to use gravity to assist in compressing the joint. I would (on a small tank < 100 gal) attach all sides to the bottom first. Simply lay the piece down. Place one of the longer pieces on the razorblades on top of the bottom. Using a needle-like seringe to apply the Weldon. Wait about 45-60 sec. Then pull out the razorblades. This should squeeze out a little extra liquified acrylic, just wipe it off with a wet rag. This should fully set up within 24 hours. In that time period, you can attach the other pieces to the base. You can also attach them to each other using the same meathod within about 5 min. of the base setting up.
In other words, the order I would suggest for attachment is:
1. Lay bottom on flat surface.
2. Place the front pannel on top of it, and attach it to the base.
3. Let it set for about 5 min.
4. Place the left on the base, and attach it to the base and front.
5. Place the right on the base, and attach it to the base and front.
6. Let them sit about 5 min.
7. Place the back on the base, and attach it to the base, left, and right.
8. Let that sit for about 10 min.
9. Place the top on the sides, and attach it to all.
10. Go to the fridge and grab that 6-pack that you had to use to bribe yourself to actually take the time to do this, and enjoy.
The hardest thing about this is to get the vertical joints to press togather. You can modify this process by attaching to the bottom, and then using the stored energy (from seperating with a spacer or razorblade) to press the sides togather. You could also attach the sides to the bottom, and then lay the entire creation on it's side to put pressure on the joint. I would recommend using a vice or clamp to compress the joints, but they have to be longer than the longest piece that you must attach. You could also make a miter-box to hold them in perfect position, i.e. level, plumb,... These were omitted due to difficulty, time, or preference.
Another tricky part is attaching the top. Remeber, this is for supporting the sides, and reducing central stress due to bowing. They need to be stout, yet functional. Small holes stregthen but hinders placing objects in decorating it, and also makes it harder to attach the piece to the sides. I would at least give about a 2" lip all the way around the tank, and don't forget a crossmember running front to back in the middle of the top. This isn't nearly as needed in small tanks as it is in larger ones.
Hope this helps, or at least gives you somewhere to start from. Feel free to ask me any questions, and if I don't know the answer, I'll look for one. I do have to remind you that my knowlege is in theory only. I have yet to embark on my tank, and have not had much experience with joining acrylic. The stuff I know is available to anyone with time to spare, and an internet link. However, I have confirmed much of my information with the acrylic dealer.
once dried. The only problem I was warned about is that the stuff is about the consistancy of water, thus must be held together for some time. As I understand it, this stuff is fairly easy to use. If you want to attempt it, I can send you some of the stuff, it's like $3 for a small can of the stuff (about the size of 1/2 of a coke can). Also the seringe on a squeeze bottle (cool idea) is about $3. I am glad to ship these at cost to anyone. Hey, I guess there's one good thing about having the worst air quality in the U.S., all the chemical/plastic plants sell their stuff cheap. Just post a message if you want anything.
)
, Alright fellers, lets figure this out. I understand their is no glue I was just checking. What I had thought they had done was heated the acrylic up and bent it into shape. I guess that is just for the super dooper aquarium manufacturers. I wonder what would heat it up enough along a straight line or in a cylindar shape? ( B I G Oven). 
