a, The octobot features include (1) the body matrix, (2) the fuel reservoir matrix, (3) printed fuel reservoir traces, (4) fugitive plugs in the soft controller, (5) printed platinum reaction chambers, (6) printed pneumatic networks, (7) printed vent orifices, (8) printed actuators and (9) moulded hyperelastic actuator matrix. All printed features are composed of the fugitive ink except the printed platinum reaction chambers (5), which are patterned using the catalytic ink. b, The storage modulus, G′, of the fugitive ink, catalytic ink, body matrix and fuel reservoir matrix as a function of shear stress. The plateau moduli of the inks are an order of magnitude higher than those of the matrix materials. c, Trace widths of the fugitive and catalytic inks printed at 450 kPa and 345 kPa, respectively, decrease with print speed. Error bars indicate the standard deviation for n = 3 measurements. d, Optical images of channel cross-sections printed at speeds of 0.5 mm s⁻¹ and 10 mm s⁻¹, which demonstrate that trace dimensions can be changed on-the-fly. Scale bars, 100 μm. e, f, Reaction chambers printed with the catalytic inks contain a platinum-laden plug, as shown in a cross-section (e; scale bar, 500 μm) and a scanning electron micrograph (f; scale bar, 25 μm).