Cut the mat of choice to fit and then punch holes to match the pattern on the cup warmer. Mark the holes from the opposite of the tray with an ultra-fine sharpie, then use a piece of stainless tubing, cut to a sharp bevel on one end as a punch. So easy.

Nuova Simonelli has nylon grills of various sizes for relatively cheap as another option:

05340023 Nylon grill 178mm X 210mm $5.40
05340024 Nylon grill 178mm X 350mm $9.20
05340025 Nylon grill 178mm X 270mm $5.00

I have 2 of the 178x270 grills on top of my Appia that work well. These are about 4.8mm thick. Not sure what size you might need, but I think these would be easy to cut down to size if needed. I suppose if you still had vibration issues with the grills, I guess you could use some rubber feet in the corners. My machine didn't have them when I bought it, so my cup warmer was all scratched up to begin with



Bottom of the grills are flat


Here's the top

RapidCoffee wrote:Blocking air flow will reduce heat dissipation inside the espresso machine. In general, this strikes me as an unwise thing to do.

+1! The manual for my Oscar warns quite clearly and prominently against covering any of the holes in the top. Of course, you could simply punch holes in the mat to avoid a new problem while fixing the original one. Cut a piece of paper the same size and shape as the mat you made, place it on the machine, rub a pencil on it over each hole to make a template, and transfer-punch the mat - taking it off the machine first, of course

I dont meant to try and speak for Nicholas, but I do recall.. possibly in a write-up he did upon recieving his GS/3, that he had found that rubber sink mat on one of the big box stores, and used it on top of his machine, just like in the OP. He did however remove a grid pattern, taking out maybe 50% of the mats material to let plenty of heat through.

For years I kept a folded dish towel on top of my Bricoletta. No problems. When I got a VBM DD I did the same thing. Within 6 months the Gicar brain case melted and totally fried rendering DD dead from lack of ventilation.