I have one heck of a mortar bed that's made of laminated 2X6's. A layer going one direction and the next going the other direction. The Idea was to have a practical, heck bent for stout mortar bed that I would not ever have to worry about. All the 2X6's were glued together and then more than I can count of deck screws going in out and sideways to hold it all together. Cracks were all puttied up and sanded square. Every corner got a metal corner bracket screwed in with 2" #10 screws. Every corner on the bottom of the bed got an eye-bolt with a 1" eye and three inches of screw buried into the wood bed. My son helped me with the steel brackets to separate and secure all the mortar pieces so everything is rock solid and with four tent pegs hammered into the eye-bolts nothing was to tip over or recoil backwards during firing. The smallest bore is 1/2" with some 1"er's and then golf ball size as the biggest. They all fit somewhere on the common mortar bed and the final shot is from a thunder mug of golf ball bore sitting next to the mortar bed.
I'm using 3mm Visco Fuse that I bought in 165 foot lengths. I finally came up with a 9" length because of timing. I wanted everything to fire sequentially and have seven pieces but a total of 12 bores to deal with. With a three shot mortar that does not have a common fuse to the bores, you have to figure out something to cut and attach fuse pieces so that the fuse will start the next fuse in line. Otherwise you'd have to run different length fuses all to a common start point and if the fuse pieces were of the same length then maybe they'd all go off at the same time? But since I wanted them to fire sequentially, I ended up with 9" pieces and then have some way to attach them as I went along.
On some connections I figured out to put one 9" piece end into one barrel and the other end into another piece's fuse hole. But there were some that I had to just nip off a 1" piece and somehow attach it to a burning fuse. So I came up with a brainstorm of using dental floss. Cheap and fine and strong, but a royal PITB. I then got a better brainstorm of using the metal twist ties that are used on some loaves of bread. Not the plastic ones, but the paper wrapped metal wire kind. I'll be doing some fuse only tests on my set up to see if that's the answer or not. In the interim I wonder if any of you have a similar display (or reason to attach different fuse lines together) just how you folk go about tying fuses together? Smithy.