The total time it takes to make is about five to six (5-6) minutes and then twenty-four (24) hours to solidify.

Materials & Equipment:

• Three (3) to four (4) jars, capable of holding 1/2-cup of fluid each.  I used four (4) clean and recycled baby food jars, and each jar holds 1/2-cup of mixture.
• Food Coloring
• Essential Oil or Room Fragrance drops (Can be purchased at a craft store, but I found one on sale for $2 at Walmart.)
• Two (2) cups of water, divided into two 1-cup amounts
• Four (4) envelopes unflavored gelatine (one 1-oz box)
• One (1) tablespoon of salt
• Kitchen equipment such as a whisk, a pan to boil the water and spoons (plastic or metal) to mix the concoction

Prepare:

• Pour a few drops of food coloring of your choice into each jar.
• Next, pour one (1) teaspoon (minimum) of essential oil into each jar.  You may want to add more if you desire a stronger scent emanating from the end result.  I did not use more than two teaspoons and was pleased with the one teaspoon result.

Boil and Mix:

• Bring one (1) cup of water to a boil.
• Add all four (4) envelopes of gelatine to the boiling water and whisk until dissolved.  (I estimate it dissolved in about a minute.)
• After the gelatine dissolves, add the remaining cup of water and then the salt.
• After the salt dissolves, remove the pan from the heat and pour into the prepared jars.  Try pouring the mixture into the jars within a few minutes of removing the pan off of the heat.
• NOTE: Please be careful as the mixture will be very hot!  My husband held the pot with a steady hand for the photo.  However the second time I did this by myself, I made a mess everywhere and spilled the gelatine mixture on the counter.  You may want to use a funnel to put the gelatine mixture in the jars.
• I used a broken clothespin to stir the gelatinous combination, but suggest using plastic spoons.  Use them quickly as the heat from the water could make them melt slightly.

Let the now fragrant gel mix solidify at room temperature for at least 24-hours.
Can you believe that's it?

The scent and solid mixture will disintegrate over time.  The one in my car has lasted over a month.  The one in my bathroom has lasted over a month but probably will be ready to clean out in another week.  I estimate that one jar would last from four to six (4-6) good weeks of scent dispersion. Make sure the lid is off the container to enjoy!

source: Homemade Air Freshener Gel (with Pictures) - Instructables