For a perfectly distributed and homogenized coffee bed you'll need a WDT-Tool. Just add two 6x3mm magnets while printing and stick the mount with double sided tape to the wall of your choice. 

I used five of these needles: https://www.shop-apotheke.at/arzneimittel/D2050806/sterican-standardkanuele-gr-2-g21-x-1-1-2-zoll-0-80-x-40-mm-gruen.htm . They are not sharp, so the risk of hurting someone is low. 
 

I hope you like it! And if you encounter any problems, let me know!

If you want to buy me a coffe: https://paypal.me/kododo :)