Cutout images of the secure continuum detections in the FFs clusters. Left: 1.1 mm continuum emission image adopting natural weighting, with colors as in Fig. 1. Solid black curves show the positive S/N contours with natural weighting, starting from ±2σ up to ±5σ in steps of 1σ, and then above ±5σ in steps of 2.5σ. Dashed curves show the negative S/N contours. In the bottom left corner we show the corresponding synthesized beam. For A2744-ID06 we additionally overlay solid purple curves showing the S/N contours from the corresponding Taper weighted image. The best-fit 2d elliptical Gaussian model is shown as a green region whose size denotes where the emission is half of the maximum. The yellow points represent the position of optical/NIR detected galaxies. Right: residual of the 1.1 mm continuum emission after the best-fit model is subtracted from the uv visibilities. The color scale is identical to the left-hand side.