You can retrofit this design easily with just about any kind of 9 volt battery clip... I've used one that has a beefy plastic housing for glue to stick to.

9 volt battery clip (link to Digikey)

Trim the leads down to about 3/4 of an inch...

Strip and tin the ends.

Solder to the PCB... positive is marked with a + on the opposite side.

Now... I'm going to cheat a little bit - I orderd 1/10 watt 0603 resistors instead of 1/8 watt 1206.

Precision is great though...

You can pick any resistor you want from about 180 ohms to 1000 ohms, the brightness will vary but so will the battery life!

0603 is small...

0402 and 0201 are even smaller - yikes!

It's a bit of a stretch, but it looks like it will work just fine.

The torch has been running for about a day with the 1/10 watt resistor in place... seems to be okay.

Still, I'd recommend using the value recommended in Circuit Playground.

LEDs have polarity... which is marked on the board with the white silkscreen and on the LED via a flattened side.

Match-em' up and solder in-place.

Trim your leads down a bit and... let's assemble!