Be aware that SCAL and the Silver Bullet need to be calibrated in order to do accurate print and cuts, so if you have not already calibrated, do that before you attempt this.
Here is the base file you need for this method. It will allow you to use a 15cm Square item of your choice to scan. Be sensible and stash a copy of the file so if you mess it up you still have the original!
Note Your paper size needs to be truly square and truly sized or this will not work. I was using origami papers, which because of their nature, have to be accurate. If you need to, just use the SCAL software to cut a 15cm square out of your paper in the normal way, to start off.
The file I link, is to be printed only - I used a plain sheet of A4. The format has been centred to page and locked so that you can't accidentally move anything. Print it off as is.
This is because there is a difference in the size on screen and what is printed from my printer. The result for me is a print, with registration marks of a 15cm square. YOU MAY FIND YOU NEED TO ADJUST THE SIZE FOR YOUR PRINTER but then again, maybe not. Mine is a Canon Pixma 3550. If you need to adjust it, scale in percentages till you get it right then save the file. In order to get the registration marks and square to print, I put two squares on top of each other. One is a print line, the other is a cut line. Once the paper has been printed, the cut line can be moved away( cut and paste to a new page in the design so you still have it) and if needed, used to cut a piece of your design paper. Again, make a copy of the adjusted file and store in a safe place.
By now you should have your A4 paper with a square and reg marks printed on it.
Next step is to cut out your 15cm square - by hand or machine. Accurately.
Black out the corners of your square paper. This is important as it gives boundaries to the scan and makes it easier to size. I tried using a border, but it was a bit of a pain to do and this works better.
Scan your paper and set the image to trace. I'm not giving you a tracing lesson here but make sure the corners are traced!
When happy with your trace, check the image size. It will most likely be a bit under 15cm square, so adjust the scale to make it 15cm square.
Centre the scanned cut lines to the square (if you have not moved anything, centre to page will work).
Place your A4 sheet on your cutting mat. Use a little glue (I used a temporary spray adhesive)to stick the 15cm pattern onto the sheet IN THE EXACT POSITION OF THE SQUARE.
Then all you do is set the software to print and cut, use your built in laser to read the registration marks and cut as usual.
Later today I intend to work out the size I need for a larger paper, so that I can actually cut out a whole A4 sheet. I'll post the file for that when I'm done, in here, so they are both together.
I think you will agree that the results are pretty impressive. It is my intention to use the file to make a mat specific to the function, by transferring the marks to a plastic mat and doing away with the need for a sheet of paper each time.
EDIT - If you want to cut scraps, just stick them onto the 15cm square and scan them just as you would a design paper!
After playing around a bit, I made this file For individual reg marks. Cut the squares in Black Paper and the 'L' shapes in White Card. I made this prototype but it will show up better if a white 'L' is lined up to the edge of the black square. The layers will help you line it up with the edge of your A4 or whatever. There is a tiny notch in the outer 'L' shape for the laser to line up with.
As long as you have your paper and the size on the screen correct, you should be able to put them on the mat around the paper edges and be able to cut the whole sheet.
So, the process for that, is scan your full page (with corners blacked out), trace and then make sure the size is accurate - i.e. 29.700 x 21cm for A4.
Pretend you are going to do a print and cut but omit the printing. Put paper on mat, with your pre made reg marks and use as normal. Do your best to line up the points well, it makes all the difference!
NB, if using larger paper, make sure to use a suitable mat size and position it so that the carriage can go completely from side to side without going into 'pass' mode.
Please, don't ask how I know about that.....:)