A proper aftershave does three important things post-razor: 1) it contains an antiseptic agent to keep your newly vulnerable skin germ free; 2) It helps soothe the skin and 3) it helps close the pores (openned from the warm water and the blade) to keep out dirt and oil.
And, like all good things - it can be made at home. Here's five options to check out, with lots variation in difficulty, complexity, and, of course, scent.
1. Bay Rum Aftershave - The Art of Manliness recently offered these two recipes for a classic Bay Rum. "West Indies bay leaf, spices, and Jamaican rum, combine to give the bay rum fragrance its distinctive woody, sweet, and spicy scent." These contain all easy-to-find ingredients, so they're a cool place to start.
2. Cucumber Aftershave Splash - This option from CraftBits is super quick and simple, and uses only three ingredients, and a microwave!
3. Peppermint Aftershave - This one's pretty simple as well, but requires a few more exotic ingredients that are most likely locally available, but'll take some resourcing from the drug and health food store.
4. Two Spirit-Steeped recipes from the wet shaving forum Straight Razor place, both using distilled liquors as their bases.
5. Some general techniques from Essortment on using spices and extracts on creating your own recipes.