I work on a Hot Head and had pretty good success making a nice "checkerboard" murrini (pics below) using the following technique:
1. Start with a gather of black wrapped on the end of a 5/32" mandrel (or similar thicker one). I do better starting on the end of a mandrel rather than working with a rod which can sometimes get too soft with the ambient heat and droop!
2. I'd wrap about 4x around with my Black (I'd use "Hades" which is nice and dense), heat to melt them all smooth, then shape into a square.
3. Using White (I use plain old moretti White), add several layers to one side of the square; be careful not to let it droop over the sides of the Black. Keep adding, smoothing and shaping until you end up with a applied amount of white so that when squared up it is about the same size as the Black square you first built.
3. Be sure to square up the first applied Black square to hold it's shape, and keep it nice and toasty so it doesn't release from the mandrel or crack.
4. Do the same thing on the opposite side of the center Black square, so now you have a Black square built right on the mandrel, and a White square on each side of the foundation Black Square. This makes a longish rectangle - Black in the center and White on each size - which is easy to keep shaped with your Graphite paddle.
5. Now apply Black again moving back and forth (first one side, then the other) to build up two Black squares, one each side of one of the White ones you just created. Your gather now resembles a "T".
6. Heat the Black applications and square them up.
7. Now add White each side - butted right up against the two Black squares you just built and atop the center Black square you first created.
8. Lastly add your final two Black squares - one each side of the center-row-end White square you built in Step 3 above.
9. Heat and true up (flatten) each side of this now rather large checkered gather.
10. Now add clear all around this squared gather. You will need to add extra clear on the four flat sides so that you end up with the encasement being round in shape.
11. Add your handles or punties - removing the initial mandrel you built the gather on - as necessary. Just an FYI, I use the steel punties purchased from Noodlesaurus as these work best for me. Heat the gather all the way through to soft and pliable and pull into a rod.
Ta Da!!!
Here's pics of how mine came out using this method. I used red and white as they were meant for "gingham" murrini to add to my "Teddy Bear Picnic" series:
Hope this helps you out!!!
De