Thanks to newtnewt, I was able to put my blush into an old vintage compact. I had been on the lookout for a compact to put my powder in, and finally found one I liked. Sadly, it needed more work than just new powder. I created a custom powder puff and added a new mirror in addition to the new powder.

Step 1: Materials

vintage compact

alcohol

acetone (nail polish remover)

butter knife

small bowl

leather

scissors

E-6000 glue

new compact

leather modeling tool (optional but recommended)

boxcutter, X-acto knife, or leather punch

fabric scrap

sock yarn

crochet needle

embroidery thread

needle

Step 2: Empty

Scrape the old powder from the compact with a fork or butter knife.

Once you've gotten the majority of it out, you can scrub the last remnants out with a sponge and water.

Step 3: Remove Glue

To remove glue residue from an old mirror, soak it in acetone. Once it's soaked for a few minutes, scrape it with your butter knife or sandpaper.

Rinse and repeat until you've gotten the glue off. Because my cover is textured, I settled for a smooth surface. There was glue left in the crevices, but I planned to cover it up anyway. It was just important to remove the bumps.

Step 4: Powder Puff

Cut a piece of fabric about a 1/2" larger than the puff from the vintage compact. I used a piece of wool.

Fold in the edges and stitch the corners down.

Step 5: Powder Puff Continued

Crochet the top of your powder puff.

If your powder puff is rectangular like mine, crochet an oblong granny square. To make it oblong, instead of square, you'll create six sets of three double crochet in the center instead of four with a larger center circle. I've italicized the changes from a standard granny square to an oblong shape.

Pattern:

Ch 10, join with a slip stitch to first chain to form ring.

Ch 3, Dc 2 (this is your first set)

Ch 1

Dc 3 (2nd set)

Ch 3 (1st corner)

Dc 3 (3rd set)

Ch 3 (2nd corner)

Dc 3 (4th set)

Ch 1

Dc 3 (5th set)

Ch 3 (3rd corner)

Dc 3 (6th set)

Ch 3 (4th corner)

Slip stitch into the third stitch in your first set

Fasten off

Add additional rounds with different colors until your puff is large enough.

Step 6: Powder Puff Continued

Stitch the crocheted top to your fabric bottom with some embroidery thread using an overhand stitch.

Step 7: Powder

Scrape the powder from the new compact into a small dish.

Add alcohol. This isn't an exact science, but I prefer to use only as much as necessary to turn the powder into a paste. If you end up with a thinner consistency, it will be fine. It just takes longer to dry.

Mash up the powder with the alcohol.

Step 8: Powder Continued

Spread the powder paste into the vintage compact.

Set aside to dry overnight.

Step 9: Mirror

Pry the mirror out of the new compact.

Press a piece of leather onto the top of the compact to create an impression of the shape and size.

Cut out the leather on the impressions.

Trace the mirror onto the back of the leather where you want it placed.

Draw an additional line about a 1/4" inside of your traced mirror line.

Use a leather punch to start a hole for your scissors. (You could also cut a slit with a boxcutter or X-acto knife.)

Cut out the inside circle.

Step 10: Mirror Continued

Use E-6000 on the edge of the hole and press the mirror firmly in place, lining it up with your original traced circle.

Apply plenty of glue to the lid of the vintage compact and to the edge of the mirror.

Press the leather into the lid.

Use a leather modeling tool to press the leather firmly around the edges of the mirror and into the lid. You don't need this tool, to make this work, but it's quite helpful.