This study verifies the body-centered cubic (bcc) formability of CrMoTi medium-entropy alloy (MEA) as a potential mold material via theoretical calculations based on the concepts of multiprincipal element alloys and practical experiments employing arc melting and additive manufacturing (AM) techniques. The hardness and thermal properties of arc-melted CrMoTi MEA were tested at room and elevated temperatures. At room temperature, the alloy possesses a hardness of 520.6 HV_0.3, thermal capacity of 371 J/(kg·K), and heat conductivity of 14.0 W/(m·K). Its hardness drops to 356.0 HV_0.3 at 600^oC, and its thermal capacity and heat conductivity increase to 446 J/(kg·K) and 28.4 W/(m·K), respectively, at 709^oC, exhibiting the characteristic of semimetals. AM techniques are efficient for fabricating highly customized molds and have been widely used. Moreover, in situ alloying can further improve the compositional flexibility in the AM process. The in situ alloying printability of two AM techniques, i.e., direct laser deposition (DLD) and selective laser melting (SLM), was investigated using a blend of elemental powders. The best densification within the AM approaches (7.46 g/cm³) is achieved using DLD, and the microhardness of DLDed samples reaches 634.6 HV_0.3. Conversely, the printability of SLM is relatively restricted. The optimal density and microhardness of the SLMed sample are 7.27 g/cm³ and 605.9 HV_0.3, respectively, which are lower than those of the DLDed samples. In the DLDed samples, the large melt pool can homogenize most elements but with a Cr burning loss. Mo melts insufficiently during the SLM process and remains a partially melted powder in as-built samples. Moreover, cracking is already inevitable in SLMed samples, indicating that homogenization can hardly be improved by applying excessive energy input. As a brittle bcc alloy, its matrix tends to fail under the thermal stress of the heat accumulation in the AM process. Furthermore, the phase transformation in a small melt pool also intrinsically harms printability for in situ alloying studies through AM. Results from this study reveal that DLD possesses advantages over SLM for the in situ alloying of brittle materials like CrMoTi MEA. Combining elements with adequate overlapping of the liquid zone could be essential for superior printability of AM in situ alloying, especially with a high ratio of introduced elements.