Pour raspberries into a large jar and cover with sugar. Pour vodka over all and close with lid.
Shake several times the first day until all of the sugar has dissolved.
Store in a cool, dark place for a minimum of one month (I recommend 6 weeks, longer is fine too). Shake every day or two.
When the liqueur is ready to be bottled, line a strainer with a couple of layers of cheesecloth, preferably butter muslin and place it over a large pot or bowl. Pour the liquor over the cheesecloth slowly letting the liquid drain while the strainer catches the solids. Repeat if necessary.
When ready, store in bottles. I like to keep one in the fridge for an icy after dinner drink!
Notes
I've found I can only get 100 proof in a large bottle of Smirnoff's; if you use another brand and a 750 ml bottle; you can just use it allI used frozen berries because I wanted to start this early when all the fresh berries at the market were trucked in and super pricey. It turned out great so I say use what you can find. If it's mid summer and fresh ones are prolific...go for it!