Ive herd of people nipping the grow tips during flowering to induce horazontal bud growth. This would certainly give it more girth dont know about the density. Also get some canna npk that makes the ladys explode in flowering.But mostly the bud structure is dependant on the genetics you have going and the way you trained your plants, indica's have a much more dense bud than sativa's .
Actually the bud structure is mostly dependant on the genetics. If you have 100% sativa's under alot of light it will still grow like a sativa with thin airy buds.
If you've got good light then try liquid bat guano! been using it for two weeks and the buds are defiintely A LOT bigger. i've been adding 1 qt to five gallons of an organic compost tea. I've been using the tea daily since clone stage and it's worked very well. Added the guano and everything got bigger.