Faza,

Ask El-timbo what putty/filler he uses. Hes the man when it comes to excellent cabinet jobs.

I have only seen people use spray bog, in a can from super cheap auto and its grey in colour. but i reckon Tim will have a better product.

p.s - what are u going to do with the inside of the cabinet.?  see what tim does with his. it gives the BEST results and looks so much better than a unfinished look.