Firstly, you will need a t-shirt.
I chose an extra large mens grey t-shirt from Primark.
It cost me £2.50.
You will also need tailors chalk, fabric paint, a paint brush, a ruler, fabric sheers, an iron, some cardboard and a sewing machine.

If the t-shirt is new, cut off any tags. I also cut off the 'Primark' part of the care label.

If you need to, iron your t-shirt. Next, put some cardboard inside the t-shirt to stop any paint from seeping through to the back. Then use a ruler and the tailors chalk to draw your design on.

Begin with the center line. Then draw a line across the bottom, ensuring the first line is perfectly in the middle. Join up the ends of this line to the top of your first line.
I then free handed the circle in the middle.

Using a thin paintbrush, carefully paint on your design following the tailors chalk lines.

When you are happy with your design, leave it to dry.
In the meantime, I folded the sleeves up twice, and pinned them in place.

When the paint is dry, follow the instructions on your paint pot to set it. Mine said to put a clean cloth over the design, and iron it on a high setting.

I then ironed the sleeves in place.

My t-shirt was too long, so i folded it up twice, pinned and ironed it in place.

Sew down the folded over sleeves and bottom of the t-shirt.

Turn the t-shirt inside out, and iron all over.

Rock your Deathly Hallows t-shirt, and make sure everyone knows that you were with Harry 'till the very end.
'always'.