Men's shirt to boys' look tutorial

So here I will show you how to turn this...

... into this.

Trousers

The body of the shirt is used for the trousers - the size of the shirt will determine how big the trousers can get. Here I used a size M shirt and made size 116 (6 years) trousers, 3/4 length.

You can use any trouser pattern as long as it fits on the shirt. I cut the pockets out of the shoulders and added contrasting fabric for waitband and inside pockets.

Make sure you leave enough fabric on the top to be able to reuse the collar (a little more than two buttons down).

Shirt

 Use your favourite shirt pattern and cut out all the pieces in a knit fabric that matches your shirt. In addition, cut out the shirt collar (symmetrical!) in a shape you like. Mine is round in the front and trapezium shaped in the back. I also cut elbow patches out of the shirt as well as the straps to roll up the sleeves (remember seam allowances).

For the sleeves I put the elbow patches on vliesofix, ironed them to the back half of the sleeves and sewed around the edge with a rather tight zig zag stitch.

Then I sewed the strap to the front of the shirt, folding in seam allowances on three sides (leaving the bottom with the strap open). I then cut a horizontal slit in the jersey fabric between the side seams and pulled the strap through to the inside.
Then I folded in the bottom edge of that little square with the button on the right side and sewed it to the shirt. Make sure the strap on the back points down towards the cuff when you sew.

I then finished ogg with a zig zag seam around the square (not necessary, really, but I liked it, and, just to make sure...).

 Close the shoulder seams and sew around the edge of the collar (serger og zig zag). Then put the collar on the inside (wrong side) of the shirt and align shirt and collar shoulder seams. Pin the collar to the shirt as symmetrical as possible. Stitch the collar to the shirt about 1 cm from the edge. Turn the shirt to the right side.

Cut along the inside of that seam and remove the fabric on top of the collar.

If you have used a single jersey, you do nor need to secure the edges. If you used an interlock jersey, you should add a zig zag or something similar to secure the edges.

I added another straight seam parallel to the first one, just because it looks good...
Assemble your shirt as usual.

 Done!