Let me start by saying this is how to make slippers for boys that are NOT my son. I learned he was really picky, and hard to please, and well later down the road I will put out another boy slipper tutorial when I figure out how to pattern what HE wants. SO you may think why the goofy picture? My son refused to walk in them so he just stuck his feet in the air, I snapped some pictures and then they turned ugly as I was trying to make them what he wanted (you will see that later) I seriously almost didn’t share this tutorial since he hated them so much, but they really did turn out cute and I think any other boy (or husband, or girl for that matter) may like them just fine. So, here you go. 
To start you will make a little pattern. I was going to offer a free download pattern for this and maybe I will someday but everyone’s foot is do different it is really just as easy to make your own. To do this trace around the foot of the slipper wearer. In this case it was my son. Then make a basic “slipper” shape around the foot tracing. To me slippers have less form of a shoe I also did a square toe since it seems more boyish. One thing you will notice from my drawing that I do not recommend doing your self is I left wiggle room or “growth room” at the top and bottom which made them a little too big for his foot, So just add wiggle room for the toes but match the heal (with a seam allowance) Then cut out the toe piece by following the shape of the toe area of the foot pattern and make it about 2/3 the foot. (again I made mine just barely over half and would recommend making it a little longer) Then lastly measure all around the outside of the foot piece. For me this was 20 inches, so I cut 2 rectangles that were 20 1/2 inches long (a little extra for the seam) and  3 1/2 inches tall. 

Here are all my pieces cut out. I used a soft flannel print for the outside and a furry sherpa fleece for the lining. 

Then with right sides together sew along the top part and about 1/2 inch down the side of the top piece. (not the toe end but the other end) Then clip the corners and turn it right side out

Then just to secure the two layers of the sole together I sewed wrong sides together to kind of “quilt” the two layers together. I just followed the lines in the print but you could do a design if you wanted. 

Then take the rectangle and sew it right sides together along the short side to create a tube. Do this with both layers and then put them wrong sides together so it looks like the picture. 

Then starting at the side seam, pin right sides together pinning the top piece to the band, as shown in the picture. Then sew in place, but don’t sew down the little flaps on each side that you made in the last step. 

Then when you turn it right side out it should look something like the picture above. (a really weird platform slipper ha ha) I also turned under the remaining edge and sewed it in place.

So I took some embroidery floss and pinched the edge around the toe and stitched some X’s so it had that moccasin look, (or at least in my mind)

Then fold the slipper in half and cut a curve in the band piece so it is shorter at the toe and then goes into the full length. Why do this now, I tried to just make the rectangle the way I wanted it but I assure you it is easier to trim away what you don’t need then trying to line everything up perfectly. So the toe length should be maybe between 1/2 and inch and 1 inch. 

Then with right sides together sew the sole to the slipper. 

Then put it on your lucky kiddo and hopefully they will love it! I thought it was too cute but instead things unfolded differently…
Me: Do you love it?
Him: No! It’s not tight enough
Me: Tight? (trying to figure out in my mind if the 3 year old is using the right word)
Him: Yeah it’s not tight enough
Me: Well walk around does it stay on?
Him: No I can’t walk it’s not too good.
Me: Well can you try?
Him: No see (waves his foot around like crazy as the slipper stays put) it’s not tight
Me: more confused than ever… well can I take a picture?
So then I snapped the picture above.

Then in attempt to make it feel “tighter” I used some knit ribbing and made a faux sock type thing and sewed it to the slipper. Still not “tight” enough for the 3 year old. So I start taking in the sides and making it smaller all around.

5 attempts at resizing it later (rough resizing might I add) I created something that looks like frankensteins monster. It is just plain hideous… I put it on his foot and he looks up at me with a huge smile and says “it’s perfect!” while flashing me a big thumbs up.
Well I really am pleased that after all of the work that went into creating the slipper that he asked for, he really only wanted a sock… So I may create a tutorial on making a pretty version of his “sock” when I sit down and make them pretty. I also have more family slippers to share, likely after Christmas. Till then I hope you have a less picky individual on your hands and enjoy what really is a fine slipper.