Trigger guard rolled edge simple to do though only when you know the trick of how to add an after market one. Though I must say not a very common request these days.
you will require either 3.5mm or 4mm thick walled or any other size you think fit, steel tubing is obtainable on this side of the pond from model builder suppliers.
Some fine DRY* sand.
Piece of flat board to accommodate the size of the trigger guard bow and then some.
Junior hacksaw blade, plus a piece of wood to have as a handle for a very short piece of the hacksaw blade,
Fast set Epoxy adhesive.
The how to >>>
Start with a length of tubing about three times the length of the bow, heat red hot and allow to cool slowly to soften the metal. put a blob of Epoxy on one end of the tube to seal it then fill the tube with sand making sure that it has no gaps then seal the open end with Epoxy.
Now bend to shape using the trigger guard as a first time former work slowly using only your fingers metal tools put dents and other marks on the tube. Work the tube until you have the correct size so it follows the edge shape of the guard.
Remove the sand then stick the tube on to the flat board so it is held firmly. Now for the blood sweat and tears part of the whole project, start by fixing a very short length of hacksaw blade into a handle, start to cut a slot along the length of tubing that is the bow then make wider with a needle file if necessary. I have also used a Dremel type of tool with a miniature cutting disk though you must make the disk as small as practical and this method work's really fast. Adjust the slot and the tubes length so that it will slide on to the side of the trigger guard edge.
Now you can go two ways to fix your rolled edge to the guard.
1 Fill the tube with Epoxy adhesive and place in position using some method to hold it in place. You must fill the tube with Epoxy otherwise it will dent easily it needs to be solid.
2 Soft solder the tube to the trigger guard making sure that the tube is filled with solder, a pencil helps in cleaning up the guard after soldering.
** You can make the ends of the tube neater by squeezing the ends gently with a pair of pliers to make them more rounded while there is still sand in the tube, but you do have to have the length right.