You don't need a panini press to make a great sandwich! A brick works very well, but you do have to turn the panini over half-way through the cooking process.
I used homemade semolina focaccia, provolone cheese and mesquite-smoked turkey in the sandwich above. The focaccia already had basil, garlic and candied tomatoes in it.
You will need:
Focaccia, cut into sandwich-sized squares (or wedges if the focaccia is round)
Condiments of your choice (pesto, mayonnaise, dijon mustard, butter, etc.)
Heat a frying pan or griddle on medium heat. Holding a bread knife horizontally, cut each focaccia piece in half to make a top and bottom. Brush the crust sides with olive oil. Spread the condiments (if desired) on the cut sides. Place the bottom half, crust-side down, in the frying pan. Top with a slice of cheese . Add some meat and then another slice of cheese. Place the top half on and cover with a small piece of parchment. Place the brick on top of the parchment and cook for about 3 minutes, until the bottom slice of cheese begins to melt. Remove parchment and flip the whole thing over. Replace the parchment and the brick and cook for another minute or two until both sides are crispy and the cheese is melted. Serve immediately.