There are many elements that are often considered only for girl layouts, like flowers, glitter, bows, gems, etc. But they can be used on boy layouts.

Glitter – Use messy glitter, like glitter strokes or splashes. Golds, blues and greens work great!
Flowers – I found that small fabric flowers work best and in solid colors like brown, blue or white, with buttons in the center.
Ribbons – Use twill or grosgrain, in solid colors or simple patterns, stay away from florals or flourishes.
Gems – Antique looking gems or dull colors like blues, golds or dark reds.

Here are some layouts that use the items above in a boy layout (click on the image for credits):

Now how can you make a layout look masculine with all the great feminine styles, elements, kits, etc? Well here are some great, and popular, items to add to a boy layout: staples, tape, cardboard, boxes, snaps, buttons, twill, hardware (screws, nails, hinges…), string, paint, stars, keys, torn paper, denim or anything that looks old and worn. There are many other things to consider: colors, textures, and age of the male. The younger the male the more feminine items you can usually add. Like babies, adding lace, florals and pastels work but for a grown man that may not look so masculine (that also depends upon the man).

If you have some tips on how to make a layout masculine please feel free to post them here.