You can take a pair of wire cutters and grab the black glass close to the soldered tip and cut with nippers...I would use some type of tape to tape actually bulb. If your careful you dont need it but first time you should...I snip a little at a time or you can use a dremel with diamond tip bit to bore out. Here's where it gets tricky and the tape helps... because when you get to the glass inside attached to the filament, it breaks loose inside and is too big to fall out of your opening, so you have to make sure your bit is long enough to go in far...hold your bulb firmly with one hand and be steady with the dremel tool inserting it in..the piece will be bouncing around inside the bulb as you hold the bit spinning inside without touching the walls. But the piece will break down eventually.... honestly I say find another project to try because I've done it numerous times and still its 50/50.
You can buy fillable light bulbs.... https://www.google.com/search?client=opera&hs=jad&ei=wUzXXJjeN63A0PEP7eeQ0A8&q=light+bulbs+to+fill+with+candy&oq=light+bulbs+to+fill+&gs_l=psy-ab.1.0.33i299l3j33i160.25325.27535..33609...0.0..0.105.582.7j1......0....1..gws-wiz.......0i71j0j0i20i263j0i22i30.bADEdfK7Hb4
Screw the silver part off with a pliers then you could put stuff inside the whole