I sleeve my cells in 37mm x 50mm x 0.15mm thick clear heatshrink then spot them with cyano to ensure correct alignment. Then I use a gap filling, UV curing adhesive between the cells. This is stronger than anything. Much More Racing straight and right angled battery bars complete the job with Corally 4mm tubes. If anyone wants clear heatshrink then PM me, i take paypal
The advantage of pre-sleeving is it allows you to strip back down to the original cell if you ever need to, it also protects the sleeve, especially on IB's which have thinner printed sleeve than the GP and Sanyo products.