I looked at small kitchen appliances to make the job of deseeding berries easier. You can see my review of the Kitchen Aid juicer here and Kitchen Aid strainer here. I'm just going to tell you this. There really is no "easy" way to deseed berries. But my tips will make the task a little easier.
Put your berries in a pot, and cook over medium high heat. Continually mashing, to loosen the seeds. I really like this pampered chef nylon potato masher. It provides maximum surface area, for mashing. I let the berries cook, until I can just see a heat bubble form. Just enough to get the berries warm.
Then scrape the berries into a fine mesh strainer. Get the finest wire mesh strainer that you can find. They tend to be expensive, but sometimes you can pick them up for around $7 at discount stores like TJ Maxx.
Having a quality rubber scraper will save you washing pans, between strains. This is a pampered chef large scraper, which I highly recommend. As you can see, there are no seeds in the pan.
Your first strain, will be the most work. Just mash and press the berries through the strainer, using a spoon, or scraper.
Making sure to scrape the puree, from the bottom of the strainer.
Then wash the strainer, with a brush, if you have one.
Set up a second pan, with the clean strainer.
This time it is important that you do not press the puree with the scraper. Instead, just tap the strainer against the pan, until the puree has passed through.
Those are the seeds from the second pass. Not bad. We are almost done!
Set up the pan and strainer again.
And tap the puree through the strainer. There are just a few seeds left at this point. I'd call that done!
Once the berries are strained, I measure the puree into 1 cup portions. Then freeze.
You should get 1/2 cup puree per 6 ounces of berries.