You can make a complete set of child safe Wolverine claws from a single flip flop and a Popsicle stick.
Target sells a pair of flip flops for $2.50.
NOTE: there is a template at the end! Print it out. The length of each blade may vary, but the width and base need to be consistent.
Gently remove the strap from the flip flop. Align the first paper template from the heel to the hole between the toes, getting the most length possible without hitting one of the holes.
Once you align all three paper templates, one from the heel and the other two from the toe, use a pen or the x-acto knife to trace them, then cut the basic shapes out completely with the scissors.
BE VERY CAREFUL: Use the x-acto knife to split the material evenly. Point the blade UP, and cut AWAY from your body, poking into the material, and slicing up and away from your hand in short strokes.
The three blades should look like this.
Cut very small slits in the base of each claw with the knife, and insert a short section of Popsicle stick.
Slip your fingers between the claws, with the Popsicle stick in your palm. The tension will hold the claw in place.
Boom, parent of the year. Best and safest $3 Halloween costume ever.
Here is a printable template based on Target's large flip flop. Print this at 100%; even if the edges get cut off, it should give you a good starting point.
If you liked this guide, check out the flip flop Freddy Krueger glove in my profile!