The most time consuming part of tack fusing stringers is laying the stringers out. Most stringer bowls start with around four layers of stringers. The stringers need to be arranged in rows. It is often necessary to use a small amount of glue to keep the stringers in place as they are arranged. Some people glue the stringers directly to a piece of paper (normal or thinfire) to make them easier to arrange.
Making an 450mm square piece will take around six tubes of stringers.
If you want a piece where the individual strands of stringers are visible rather than fully fused, you will need to fire to as low a fusing temperature as possible. The precise temperature will, of course, vary by kiln. Most kilns will achieve tack fusing results in the range from 700 to 730C. Fire as quickly as you would like to around 675C, then increase the temperature very slowly, 50C per hour or less. You need to watch closely as the temperature approaches 700C. When the top layer of stringers begin to sag, start cooling the kiln. Firing too high will lead to a flat piece with no feel of the individual stringers.