Make a Bedcap

Something I believe in firmly are chores for children & letting them get a sense of accomplishment from a job well done. Making the bed is a very basic job & instantly makes the room look 70% clean. I start bed making at age 2 & generally help w/ it but so far it has been difficult to not set them up for failure w/ their types of beds ie. bunks w/ rails.
I have tried everything, especially as most of the blankets we own are not twin sized. We've had the added difficulty of putting a too-large blanket on a bed & all 3 of them hate a top sheet. I'm not sure why, they all like being in my bed w/ it's top sheet. I generally just fold the top sheet in half on top of the plastic mattress cover & cover it w/ the fitted sheet to put an extra layer underneath. Sleeping on only the fitted sheet over the plastic makes for a sweaty night.
In the colder months I just had them fold the comfortors in half like a sleeping bag, it's easier to make that way. But when the inevetible night accident occurs it's incredibly difficult to wash & nigh impossible to wring. I can, but it's a herculean effort & puts the scheduled laundry on hold, especially as that is not laundry I let hang around more than a day.
I went online to see how other parents handled this & found something called a bedcap. It's basically a fitted comforter w/out all of the overhang. I was pretty disheartened when I saw the average price was $110.00 for a single set of bedding. I already had a ton of bedding so I figured I'd just try my hand at it myself.

Here's the original blanket, for a double bed. Their mattresses are "bunkies" which I think is the same size as twin but much thinner.

Measure your mattress. I disremember but I think this was a 11x14 rectangle.

Remove some fluff to facilitate ease on your machine.

I had to go back & cut about a 4" strip up either side to get rid of too much overhang. Do that before you pin your square.

I just used a zig-zag all the way around.

A new box seam!

I didn't have it on the bed but this was how I was having them fold the too large blanket on the bed in the morning during make-up. W/ one end boxed, it really makes folding/ storage of the blanket easier & neater
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The completed & made bed. It's actually too hot for these comforters now, she just sleeps w/ a light pink baby blanket at night.

 All of the overhang there is. If she wants to tuck it in I'll be thrilled, but that's not something I plan to enforce as this isn't all that messy looking.

A view of the newly boxed in end. There you go! You've just saved your family $100.00 & made the mornings more peaceful w/ happier & proud children.