This is such a simple and fun gift idea for the dad in your life. It really is very easy! So if you are looking for that very last minute idea - this won't look last minute at all. Kids can help with this one too. Decorating the bottle or making tags is a perfect way to include them.
What you need:
6-8 oz of beer (any will do)
8-10 oz of clear/fragrance free shampoo (baby shampoo is perfect)
a bottle or container to keep the shampoo in - I used just an old condiments bottle that would have ended up in the recycling (I like to keep these types of bottles just for these occasions).
First you need to place your beer in a non-reactive pot, like stainless steel. Bring it just to a boil and then turn it down to simmer. If you are adding dried lavender, calendula, etc. add it now. Let the beer simmer into a reduction for about 25 to 30 minutes. If you are wanting to use a tea concoction to add to it, just go ahead and make a very small amount of tea separately (an ounce or two), like chamomile or green tea, and set it to the side.
Now you can add the cooled beer (and tea if you made some, but remember it should only be an ounce or two) to the bottle with your shampoo. Make sure it is a good consistency. If you need to add a little more shampoo, go ahead. You can also add your fragrance oil at this time if you would like to, a few drops should do. And something like tea tree or coconut oil can help with scalp issues.
For my beer shampoo I added calendula, chamomile and an a few drops of scented oil for fragrance.