I am going to make a 6 inch PVC Cap from PVC pipe only. For this you need a cutter and adhesive . This bigger size cap cost a lot so i made it from the 6" pipe only but cutting a little bit & used it in Hydroponic project works flawlessly. Its quite easy to make all the items needed are household items. You can also make it for any bigger size pipe cap with this process.

Supplies

This are the tools you need for this project:

PVC Pipe
Hacksaw or Angle Grinder.
Araldite Adhesive
PVC Cement
Hot Air Gun (optional)

Step 1: Cutting the Pipe

You can use Hacksaw to cut the pipe. Though i used Angle grinder to cut it saves time & energy.This bigger pipes have one end is little bigger so that it can be inserted to another pipe to make a long pipe. First you need to cut that portion this will be used as pipe cap side. Next you need to cut a 8 inch length from pipe. Then again cut it vertically in two piece. This will work as a pipe cap back base after straightening with heat.Check the image & video for details.

Step 2: Straightening the Pipe Cut

Now you have to straighten the 2 cut piece of PVC pipe.There are 3 ways to do it. Simple put the PVC cut piece in a boiling water for 2 minutes. Next take it out & put under heavy pressure to straighten it. Or you can heat the cut piece in stove flame for 1/2 minutes & when the sides are bending put under heavy pressure to straighten it. Last way is to use the hot air gun.Remember you need to move the PVC piece constantly while heating it so that whole portion is uniformly heated.

Step 3: Making the Circle

After straightening the PVC piece draw a circle. This circle should be at 5 mm bigger than the pipe outer diameter. Next cut the PVC along the line of circle with Hacksaw or Angle grinder. Also you can use a jigsaw to cut it.

Step 4: Joining

Last portion is now joining the 2 piece. First apply thin layer of PVC cement & fix both circle.Put ressure on it & let it dry for 2 hours. Next apply Araldite to the outer/Inner side of the joint. & leave it for 2 days to dry. Now your PVC pipe cap is ready to use. I used this for Hydroponic project & it works fine no issue.