Sinsation

Im working on a 2D Minecraft and ran into a small problem.
Im in the process of adding trees. The wood generation is finished and works great but the leaves is what I would like help on.
I could easily make it so it spawns a certain cluster of leaves around the top block of wood or something like that, but what I want is something a bit more random.
I want it to create a random cluster of leaves around the top block so its different every time and appears more natural than having every tree have the same leaves around it.

Is there a certain type of formula or algorithm to do something like this? If so please help me out and let me know.
Thanks!

I'm not very good at finding problems with code so I really need to ask for help from you guys

When the player collides with a block it uses this code:

Found = 0;
for( i = 0; i < global.AvailableInv; i += 1 )
{
    if( global.Inv[i,0] == other.Name )
    {
        global.Inv[i,1] += 1;
        Found = 1;
        break;
    }
}
if( Found == 0 )
{
    for( i = 0; i < global.AvailableInv; i += 1 )
    {
        if( global.Inv[i,1] <= 0 )
        {
            global.Inv[i,0] = other.Name;
            global.Inv[i,1] = 1;
            global.Inv[i,2] = other.RealName;
            global.Inv[i,3] = other.sprite_index;
            break;
        }
    }
}
with( other ) instance_destroy();

It looks good in the inventory hotbar and everything then when I right click it just spawns another player.( obj_player );
On right click code:

if( !instance_position( mouse_x, mouse_y, block_parent ) && !instance_position( mouse_x, mouse_y, obj_player ) )
{
    if( global.Inv[global.CurrentInv,1] > 0 )
    {
        instance_create( ( ( mouse_x div 32 ) * 32 ) + 16 , ( ( mouse_y div 32 ) * 32 ) + 16, global.Inv[global.CurrentInv,2] );
        global.Inv[global.CurrentInv,1] -= 1;
    }
}

If you need any more info or code just let me know.

I am currently in the process of making a Tower Defense with a sort of "Defend your country" kind of theme.
Im a fairly decent coder but my spriting skills is quite frankly, awful.

Im just wondering if someone could create a few sprites for me:
1. A machine gun type turret
2. A missile launcher turret
3. A air-lock turret( Only shoots planes and that kind of thing )
4. Flame thrower turret

These should all be based on the military and should all have the same theme.
Any help would be appreciated, thanks guys!

Details:
Size: 32 x 32
Colors: Grey or white - metallic( looking ) if possible
Perspective: Top-Down