Homemade nap mats?

I'm this granola wannabe, or a stay-at-home-mom wannabe, or just nuts.  I will not deny, I am potentially all three.  Why if I'm walking daily on a tightrope, would I EVER want to do anything homemade?

Today I got a hair-brained idea that I would make, yes MAKE, the twins nap mats they need for school this year.  Nap mats are these all-in-one mat/sleeping bags, that roll up with a strap and are washable.  The nap mats online are not outrageously expensive, and I can afford them, however my hair-brained idea is that 'wouldn't it be fun to have them pick out their own fabric, and make it myself?'

Oh brother!  I often think of these 'wouldn't it be fun if...' and they are NOT usually not in the best interest of:
1) my time
2) my sanity
3) my pocketbook

The keyword 'my' being everyone around me, including Wonderful Husband and my kids.

This goes along the same thing that I want to be a farmer.  Why would I want to do all this?  Maybe it's idealistic, maybe it's romantic, or maybe, just maybe, it is fulfilling the crafty side of myself that is lacking in my daily grind.

What is crazy about this home-made nap-mat is:

#1: I don't have a sewing machine.   I called my sister - her's is broken.

No problem, I say!  I can buy one...it can be my early birthday present.

#2: How much time will this take?  In all reality, I don't know how to sew.  I have faked it about 4 times in my life with curtains.

No problem, I say! We need the nap mats in 3 weeks from today.  I have a 1 week break from painting class, and a break from physical therapy.  I don't want to jinx myself, but on the 18th, there is NOTHING on our calendar.

#3: Why would I WANT to do this?

It's obvious, I say!  I could be doing housework, or even fun family time, play time, or pool time?  The answer...respite.  Sometimes I need a break from adventure & challenge myself.

This is nuts...we will see how far I get when I visit the fabric store sometime soon.  'Sometime soon?' Didn't I just say I had 3 weeks to do this?  Guess I will be visiting the store sooner than later.  Even as I type this I know it is a bad idea...but why can't I stop myself?  I already told you in the first sentence 'I'm nuts.'