For a single crystal of TmGa3, two-dimensional angular correlation of positron annihilation radiation spectra were measured and subjected to a deconvolution algorithm based on the Van Citter iterative method. The three-dimensional electron-positron momentum density was reconstructed both via the Cormack and a modified Fourier-transform-based method. After the 3D LCW transformation, the resulting k-space density was in fair agreement with band structure LMTO calculations. In particular, the use of deconvoluted data helped to reveal small details of the Fermi surface in the 6(th) band.