30" 1-1/4" PVC
36" 1/2" PVC
1x 1-1/2" ABS Wye Fitting
1x 1/2" PVC Slip Cap
1x 1/2" PVC Threaded Cap
2x 2 1/4" PVC Slip Cap
3x 1-1/2" x 1-1/4" PVC Bushing
1x 1/2" Slip to Threaded Adapter
1x 1/2" Foam Pipe Insulation
1x 1/2" Elbow
1x 1-1/4" x 1/2" Reducer Coupling
I purchased all of the parts new for just under $23. I did not have to buy any of the tools.
Dremel or Sand Paper
Pipe Cutter or Hack Saw
This dredge is not my original design, it's based on this: http://www.youtube.com/watch?v=YCozzarSk5A
Please note I am not responsible for anything you do, so please only use my instructions as guidelines. Use proper safety equipment and common sense. Also check with local laws to make sure you're allowed to use a dredge in your local area.
Step 1: Step 1 - Drill Cap, Sand 1/2" Adapter
The easiest way to find the center of the circle is to place a square over the circle, lining up the the point on the edge of the circle. Then mark the spot where the square goes outside of the circle. Draw a line between two marks. Repeat this again by moving the square part way around the circle and drawing another line. Where the two lines intersect is the center of the circle.
For more in-depth instructions:
Next you'll want to use a dremel or sand paper to sand the PVC Bushing (1/2" slip to 1/2" threaded) so it can fit inside the 1-1/4" pipe.