I had some beam belt strips laying around, and thought I could give them some use.

In Practice, you could use the strip for making a Hair Bun without using the fabric, but definitely it will looks much much better if you upgrade it a little, covering it with a fabric similar to your hair color.
I hope you find this useful too! :)

It is time to get ready for the summer, and bring all the hair up.

Supplies

Materials:

2x beam belt strip (using for protecting your trousers when cycling)
1x piece of fabric similar to your hair colour (at least, 4 times the size of the beam belt strip, plus margins all around)

Tools:

1x scissors
1x sewing tools (you can do it by hand with needle and thread or use a sewing machine)

Step 1: Take Meassurements, and Mark the Pieces to Cut

Position one of the beam belt strip over the fabric and mark its shape leaving around 1.5 cm all around the perimeter.

(Tip. Leave a little more than 1.5cm, like 3 cm or so) on the longest length, so that it will bend easier later)

Step 2: Cut the Fabric Pieces

Cut 4 fabric pieces of that size.

Step 3: Sew the Pieces to Join Them

Sew the 4 fabric pieces together, as sketched in the image on Step 1.
Best part is, it doesn't really matter how good you are sewing, as the piece will be hidden under your hair. Therefore, it is the perfect project to get your hands on if you are a beginner!

Step 4: Dress Your Hair!

Put your hair between the 2 strips (Like a pincer)

Step 5: Roll the Hair Pinced in the Strips

Start rolling all your hair (pinced between the 2 strips), till you have it all rolled.

Step 6: Bend the Strips

Because the strips are meant to roll, just bend the strips and they will roll together with your hair, creating a nice hair bun.
Move your hair a little, to ensure you are covering the strips and no one could see the secret beneath.