Nasal with misters works VERY well.
HPBCD (depatabable necessary) complexed 25i @ 500mcg via this roa is very intense in terms of come-up, and i'd even say its stronger than buccal. One of my favorite nbome roa's. Theres a bit of mild irritiation, but its hardly noticable, and 25i hcl w/hpbcd is soluble enough in water, that a few squirts up each nostril is ~ 500mcg. IIRC, the solution i had was ~90ug per spray. But, its not super accurate, as the sprays are not allways the same volume, if you get the technique down right, can measure out nbomes and mix them up this way, and determine the ml concentration on average of one spray its an excellent roa.
I sprayed 10 mists into a plastic spray bottle cap (~12mm diameter) and used a mg scale to determine the amount of water, 1g water/1ml. I don't think the negligible amounts of nbomes are necessary to take into account in terms of volume increases, but if you make a strong solution (not recommended) its a factor to consider. My sweet spot was 3 sprays up each nostril for ~500mcg 25i total.