Vent warm humid air into your house from the dryer. Don't send your nice heated air outside. When it warms up outside, quickly configure the lint trap to vent to the outdoors and save your air conditioning.
Step 1: Cut the Holes
Cut 3 vent holes in the lid of a 5 gallon bucket. I am using a 4" can as a template, so that I will ensure a snug fit.
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
This is the bigger of the 3 vent holes. Air from the dryer exits from this vent into the room. It must be at least the size of the 4" vent coming in or bigger. 2 layers of window screen wire. Attached with glue gun on the bottom of the lid. Added little more hot glue for the screen wire on the top of the bucket lid, just to make it easier to clean and stronger.
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
Attach cans with hose clamps. (I currently only have one can, so on the other hose I had to make due with foil tape that I had in abundance.) If 4" cans aren't around, any hardware store sells the proper fitting for a dryer hose for 3 bucks or so, and it probably can be cut in half to do the job for both vent hoses.
Step 4: Weighted Cap
Top of vent hole cover diameter 4 1/2".
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
Partially fill the bucket. The vent hose does not touch the water. It just blows on the surface of the water and the lint sticks.
-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.