Step 1: Cut the Holes
Diameter of the first 2 holes is slightly over 4" to accept the 4" dryer vent hose. (A jigsaw cuts the best, a drywall jab saw wants to get stuck. I used a utility knife. Scary!...but the cut was great.) The third hole is a half inch bigger (4 1/2" diameter) so I can use the scrap as a cover for the unused vent hole. I am using cans that just happen to be the right 4" size. The cans will be used later to stiffen up the ends of the dryer hose.
Step 2: Screened Vent Hole
Most water based lint catchers don't bother with any kind of screen, and a small amount of lint escapes. Alternative filter: pantyhose. Something that will show the lint when it has blocked the filter. But I wouldn't recommend something that can't handle humidity such as cheesecloth or a sock. 100% silicone can be used as an adhesive rather than a glue gun. Painter's caulk won't work. It's not waterproof.
Step 3: Attach Metal Sleeve
Step 4: Weighted Cap
On the bottom of the vent hole cover, I added some weatherproofing foam. The foam strip didn't want to stick, so I hit it with the glue gun.
Step 5: Add Water and Bleach
-Not for use with gas dryers.
-If used in a small room, keep the door open while in use to avoid too much heat or moisture to build-up.
-Add a cup of BLEACH to the water to keep stuff from growing. Prevent Legionnaire's disease. I would guess that a toilet tank drop-in tablet would work too, like the one Clorox makes.
The lint trap has been in operation for one month to date as of this post. About 2 1/2 gallons have evaporated in that time. I go through about 6 loads of laundry a week. It still maintains a faint bleach smell, so I am reassured the bleach hasn't dissipated yet. The trap has been successful in keeping lint from accumulating all over my laundry area.