In high-power laser–plasma experiments, low-density porous materials with high specific surface areas are more advantageous in producing a controlled low-density plasma compared with their bulk counterparts because the near-critical density region in the wavelength range of the high-power laser is between the density of solid and liquid phases. Some of the methods used to reach critical density include using cluster targets[1] and pre-laser irradiation on solid film[2]. However, it is difficult to control the density using these methods. Moreover, a dedicated target equipment and an additional laser are needed. In a recent laser–plasma interaction study, Yogo et al. reported that the picosecond relativistic-intensity (>1018 W cm−2) laser pulses focused on a solid film target can generate nonlinear electron acceleration and high-efficiency ion acceleration[3,4]. Their results indicate that picosecond relativistic-intensity laser pulses focused onto the near-critical density targets lead to a higher plasma heating efficiency. For example, efficient ion acceleration and magnetic reconnection are demonstrated using picosecond laser and low-density targets[5,6]. Resorcinol/formaldehyde (RF) aerogel is a notable laser plasma target material owing to its fine network structure, low density of 10–200 mg/cm3, transparency in the visible region, and low-Z element (hydrogen, carbon, and oxygen) composition[7,8]. Shell-shaped RF targets have been developed for inertial fusion experiments[9–17] and its cryogenic targets[18,19]. Low-density materials have low mechanical strengths. Therefore, a holder is needed to support these materials during the shaping process[14,20,21]. Fabrication of deuterated targets is also important for inertial fusion experiments. However, controlling their shape and density has proven to be difficult owing to their high reactivity at room temperature[22–24]. Recently, low-density targets, in the form of thin films and flat-surface targets, are being required for laser acceleration experiments whereas deuterated targets are useful for distinguishing the origin of the generated proton or deuteron ions. The chemistry of RF foam fabrication has two kinds of electrophile substitution reactions to resorcinol, which is a very reactive aromatic compound, as shown in Figure 1[25,26]. The first reaction is the attack of formaldehyde, forming a methylol group (–CH2OH) at the aromatic ring. The second reaction is the attack of the methylol group to another aromatic ring, forming a polymer and crosslinking. Based on this chemistry, the fabrication process has two steps and each step is slightly different. In the first step, a linear polymer is formed and a viscous polymer solution is obtained from the two chemical reactions described previously. The second step is gelation based on crosslinking. In general, molding should be done after the first step for the viscous solution around 30 mPa s. Furthermore, the solution exchange and extraction process may induce expansion or shrinkage of the gel. Therefore, the target fabrication should consider such volume changes. The purpose of this study is to fabricate disk-shaped RF foam targets for laser–particle acceleration experiments. To make disk-shaped and polymerized targets at room temperature, a paper holder was filled with deuterated resorcinol, formaldehyde, and heavy water (D2O). After polymerization, the D2O was replaced with acetone, and the target was dried using the supercritical drying method. The fabricated target has a thickness of 100 μm and a density of 30 mg/cm3. We found that the polymerization rate and the viscosity during the polymerization process were different compared with a normal RF (n-RF) foam.