final String initials = "AC";
final Context ctx = getContext();

Builder builder = new Builder();
builder.fontSize(Utils.dpToPx(24, ctx))
        .height(Utils.dpToPx(40, ctx))
        .width(Utils.dpToPx(40, ctx));
        
Drawable initialDrawable = builder.build(initials.toString(),
        ctx.getResources().getColor(R.color.blue));