The short answer is, "yes, you can!".
If you want to get into pressing flowers, but do not have a traditional flower press, we do have a workaround. A traditional flower press will give you the best results and we highly recommend you making one. We do have a video on YouTube that shows you how we make all of our flower presses. But if you haven't yet made your own press, but want to get pressing or want to take our "How to Press Flowers" course but don't yet have a press, there is a work around.
When we first started our business, we gained business more quickly than we could build our presses and so we improvised using bricks and garden pavers stolen from our own garden. All we did was stack bricks or garden pavers on top of our stacks of pressed flowers. You don't want to add too much weight all at once before the flowers get a chance to press down.
On the first day of pressing we would add 2 or three bricks on top.
On day two of pressing, we would swap out the bricks for heavier 12"x12" garden pavers.
On day 3 we would add on a second 12"x12" garden paver.
And then maybe even add on a third. If you were pressing sunflowers, I would say the more weight the better and definitely add a third paver, or more bricks, or a weight, or a dumbbell.
When you first start pressing the flowers, the stacks will be quite teeter-tottery, so we recommend stacking them next to a wall, so your leaning tower of pisa will have something to right itself against.
And that's it!