Hey Everyone :)
My problem is that i havent a device where i can practise lower back raises/hold :/
With which devices are you doing that?
I'm not sure what you mean either :)
Probably the surface that you hold on to with your arms. You can try out various stuff (if they are sturdy and they won't break, so be careful): A bed, sofa, chair, table.. Anything you can think of
Another guy already asked this, I'll tell you the same thing I told him. Use your bed or a table or a surface that half of your body can hold on to while you do the exercise.