painting/water sealing malemine?

[Kathy]

ive got this ugly fake wood cradenza im converting into a corn cage. if I use one of the water sealants like Polycrylic, is it alright to paint with acrylics directly on the malemine first, wait for it to dry, then use the polycrylic?

Also Ive got these drains that I am going to use for vents, can I use the polycrylic to cover the holes, should i put the vents on the inside or outside of the enclosure? (the back where the holes will be for the vent is about 1/4" thick, so if the vents are on the outside of the enclosure there will be a little ledge on the inside)

I have 2 drain covers, should the vents be at the top or bottom, or one of each?

Thanks for all your help, as you can probably tell ive never made anything before hehe