Begin by making sure that the small ends of the funnels fit snugly inside the ends of your PVC elbow joints.
Paint adhesive on the ends of the funnels and slide them into the elbow joints. Paint another layer over the top of the area of the funnel which connects with the joints to make sure that they will be airtight.
Set the funnels aside for a moment and take up the PVC pipe.
Use your measuring tape to mark out two lengths, each 6 inches long. Use your hacksaw to cut the pipe in half and make sure to trim the edges of the pipes free of any loose plastic scraps afterward.
Use more adhesive to connect the pipes with the Y joint in the same fashion as you did with the elbow joints.
Again make sure the seal will be airtight by painting the outside of the joint with adhesive as well.
Connect the other ends of the pipes to the other ends of your elbow joints using the same double layer adhesive method, making sure that the funnels are both arranged to point away from the Y joint.
You should be able to place the open ends of the funnels flat against the ground and the back of the Y joint should point to the ceiling. Once all the seals are dry you are ready to fit the back of your Y joint into the vacuum extension hose. You could adhesive this in place if you’ve got a spare hose so you can still clean with your vacuum when you want to. But I would suggest a few solid layers of duct tape where the back of the Y joint fits into the hose. This also allows you to adjust the suction pressure at will if it’s initially too strong by simply poking a hole in the tape to divide the suction across three ports instead of two.
Use your vacuum bra by fitting the funnels to the bare chest and connecting the hose to the vacuum.
A whisper quiet model vacuum cleaner would be a good thing to have so the noise doesn’t bother you after a while. After starting, the force of the suction should be enough to keep the device attached to the chest without the aid of straps if you’re sitting or lying in bed.