Have you seen that there are ready-made windows in that size:
http://www.byggmax.com/se-sv/Prod/PID-120606.aspx
http://www.byggmax.com/se-sv/Prod/PID-120606.aspx
If it's a playhouse, you might want to go with plexiglass.
Build a frame using, for example, 21x69 planed wood (screw and glue the corners), and then an edge strip of 8x21. For the window sash, you can use 21x44. Join "half and half" at the corners and glue them. Then, just rout a rabbet for the plexiglass and secure it with synthetic putty. Screw on some simple hinges and paint the whole thing.
It's a good idea to plane the bottom of the frame slightly angled before assembling it, so that any rainwater can drain out.
Build a frame using, for example, 21x69 planed wood (screw and glue the corners), and then an edge strip of 8x21. For the window sash, you can use 21x44. Join "half and half" at the corners and glue them. Then, just rout a rabbet for the plexiglass and secure it with synthetic putty. Screw on some simple hinges and paint the whole thing.
It's a good idea to plane the bottom of the frame slightly angled before assembling it, so that any rainwater can drain out.
I had some old windows left over that I used. Just took the outer frame and cut them down to the right size. With this, I got both hinges and metal angles in the corners. I then cut the glass down to fit. Check on Blocket, I think you can get a window for under 500:-
Buy ready-made windows at www.blocket.se you cannot build windows cheaper than you can find used windows for there. Then you also get glazed real windows.
What should I go with, plexi or regular glass?